Why might it not be a victory for free market, free culture that aggrieved people (who may or may not be the company's actual audience) are able to pressure a company into changing plans for its cultural product/art, as in the recent Batgirl "Joker variant" cover controversy, which ended with a planned cover cancelled?
Between Peter Suderman and Nick Gillespie's writing on it here, I think you have most of the background necessary to understand what happened, and why, and why the principles behind the story might be interesting beyond the specifics of the grievance.
This discussion will try to avoid the specifics of why people wanted to make the expression in question disappear—a comic book cover that showed the Joker menacing a weeping Batgirl (a fictional villain who has done terrible things to that fictional hero in a famous past story called Killing Joke, definitely including crippling her and by implication including raping her). Details both behind the scenes and in front might exist that those who actually care a lot about what is on the cover of a Batgirl comic book might have followed more closely than I have. (I am a fanatical lifelong fan and friend of comics, including superhero ones, but just don't happen to be reading or following that title.)
Nothing foundationally and inherently libertarian is implicated in this story. The cover cancellation was, in its way, a market transaction. No state ordered anyone to do anything; no one threatened D.C. with anything other than something they have the perfect right to do, which is to not buy something or to denounce that thing and the company that distributed it. I understand that some people on the "keep the cover" side did more and worse than that, and threatened actual physical violence against their ideological foes in the debate. That is neither libertarian nor decent, though I question that the very violent fervor with which some assholes on the Internet stood up for the cover adds any extra legitimacy to D.C.'s decision to quash it.
Grant everything there is to grant: it is anyone's right to denounce; it was D.C.s right to react to it any way they wanted; that artist Rafael Albuquerque stated that he wanted to kill it; that the creative team on the actual comic wanted to kill it; that it doesn't tonally fit with the current comic. It may even be great for the world and the future of humanity that this particular cover never appears physically on paper, stapled around a few dozen comic book pages, but merely will appear all over the Internet in profusion forever.
Granting all that, what larger meaning is there to this story, if any, such that a non-Batgirl reader might care?
One can see the controversy as either a merely interesting or even laudatory example of how in modernity concerned audiences for artwork or products (or, as I and others suspect but can't prove, aggreived folk on the Internet who weren't a big part of the potential audience) can communicate with artists and publishers, turning formerly one-way hierarchical relationships into more fluid and horizontal ones, allowing more people to get more of what they want and proving the power of the audience and the growing and responsiveness of Big Culture to consumer demand, just a sign that we are living in an age where consumer agency is growing in fascinating new ways..
That's not how I see its core meaning, and so can't celebrate the outcome. While that outcome is not inherently unlibertarian in an obvious way, it impacts various penumbras, as the Supreme Court might say, of what is valuable about a liberal culture of free and open expression. If this incident becomes a bellwether or how our culture will work from now on, it will be a precedent we should regret. To be less oblique, I don't like the idea that an angry mob on the Internet can get artistic products pre-emptively cancelled because they don't like the product, for whatever reason.
Censorship in the political and legal sense requries government action; but libertarian disapproval of the state is in fact rooted in the fact that it is prone to do things that are inherently not good things to do. The state does some potentially good things that are only problematic because they are being done or financed by force and violence; the state does some bad things that are problematic regardless of the entity doing them. Intolerent attempts to repress culture, to shut up expression that is disapproved of by either majority or minority, is one of those things.
The culture of boycott and anger about art or belief or words is not inherently unlibertarian. But perhaps it is dangerous to the truest and richest possibilities of communication and expression that should characterize a post-Enlightenment society that respects the Voltairian epigram about disagreeing with what one says but defending to death one's right to say it (not, that is, disagreeing with what one says and letting the people who are paying to distribute that saying know that we strongly disapprove of it and would rather it not be said in public and will punish you with obloquy and boycott if you continue to say it.)
Why are libertarians so often so annoyingly disagreeable about standing up for horrid sayings, beliefs, thoughts, and images? Sheer horridness, maybe, but also perhaps there are sociological reasons that libertarians—surrounded by a world of discourse and people who believe and advocate things they believe are the greatest of evils, state coercion and violence—tend to find it harder to get particularly angry enough about the stories others choose to tell, beliefs they choose to have, things they have to say that strike others (or even themselves!) as bad. Those who support any power, public or private, to quash expression might want to remember that the specifics of what it is OK to say can and will change, not always in your favor, which is why it's safest to avoid the fallback position of "It's only OK to say and think things and make art that are OK."
Libertarians tend by nature be slow to decide that error has no rights, both because we think most of the world is in error on key things and are acutely aware that the majority thinks we are in error, often grave and evil error. We can nod when good modern liberals point out sagely that "saying 'shut up' is an act of free speech" but also believe that is a sterile, often destructive, unnuanced and unrich form of free speech, not one to celebrate too quickly. It sets in motion a game where expression is decided by loudness and the strength of one's sense of grievance, and that seems like potentially a bad game for anyone who values the ability to speak their thoughts, speak not their thoughts, or make art.
Everyone's sense of where the culture is tilting on inchoate matters like attitudes toward free expression are going to be personal and difficult to prove. But I have a sneaking sense that pre-Enlightenment attitudes roughly summable as "error has no rights" (it's just what the tribe thinks of as error that changes) are arising with pride in many communities of discourse.
Maybe I pay too much attention to things people say on Twitter and Facebook. Still, it's hard not to derive these senses of culture from personal experience, and in my experience the idea that some expression, ideas, and beliefs just should not be out there and deserve some form of punishment even if not arrest seems stronger than I remember it being 5, 10, 20 years ago.
That's not an idea conducive to a healthy, rich, fecund, liberal culture of a sort I'd want to live in. I fear genuine tolerance of expression is getting weaker in America's educated classes, and I see this Batgirl controversy as a bad example of that. (Josh Blackman has a less solipsistic take on the idea that the First Amendment is losing its hold on a class of American's liberal intelligentsia, seen not as a core principle but as just one more weapon for the powerful to punch down on the downtrodden.) Again, one can believe that private attempts to quash expression are also a bad thing without losing one's libertarian cred, I hope. One might believe it's a bad thing for the same reason you think it's a bad thing for government to do it—just as one would I hope oppose private wholesale murder of the innocent and destruction of property for the same reasons one opposes government wars. It's not always the case that libertarians hate the government just for being the government. Sometimes we hate it because it does things we think inherently worth hating.
There is an apparent self-undercutting quality to saying it's not great for a healthy libertarian culture to tell others to shut up. To say that is to do the very thing you are saying is a bad thing: declaring some expression best avoided. Those folk strongly encouraged by the victory for feminist, anti-rape, or merely consumer-power of the Batgirl cover controversy are merely saying the same thing, right?
But still, something rich and valuable might be worth preserving about a culture of expression that tolerates everything but intolerance.
Not intolerance in the colloquial sense of not liking or supporting or approving of some set of behaviors or people or ideas, but intolerance in the sense of not tolerating expression itself.
An overweening busybody concern with what other people are saying, thinking, publishing, drawing to the extent one wants to make it stop feels unlovely. A culture where it becomes customary for people who don't approve of art and expression to pressure—even intellectually pressure—publishers and artists into eliminating that expression or art isn't the culture I prefer to live in.
This sort of intellectual turnaround always feels cheap, and yet here it seems helpful to remind people of the principle behind the particulars: don't you imagine that the distribution of approval of how this cover controversy went down vs. those bothered by it would have been different if this cultural conflict, or some other future one, arose from avowed Christian traditionalists/moralists condemning something for violating their sense of propriety and successfully getting a major media company to suppress work based on their offense?
I've never been a big fan of the concept of false consciousness, but the concept of duress has some intellectual validity. So I wouldn't necessarily trust the truly voluntary nature of the expressive culture that results from artistic decisionmaking triggered by popular anger becoming common. That's why, though there is nothing at heart "unlibertarian" about anyone's stances or actions re: the Batgirl cover, I have a hard time celebrating it.