Libertarians? What Libertarians?
I don't see any reason to believe it would be smart for a major political party to deliberately aim at the votes of some libertarian constituency. The reason is that, to a decent first approximation, about zero percent of the electorate is primarily motivated by a principled opposition to state coercion. We're not literally talking about zero people, I know some of them, and some write blogs, but it's genuinely a rounding error in the scheme of things.
And more specifically on Dems who think they can win over this possibly phantom constituency, he reminds them--they ain't libertarian, even where they might think they are:
a lot of the views liberals tend to think of us libertarian-ish liberal positions aren't actually especially libertarian at the end of the day. For example, liberals, like libertarians, don't think the coercive authority of the state should be deployed to discriminate against gays and lesbians. Unlike libertarians, however, liberals generally think the coercive authority of the state should be deployed to prevent discrimination against gays and lesbians. We think that landlords shouldn't be allowed to refuse to rent houses to gay men, that bartenders shouldn't be allowed to refuse to serve them, that employers shouldn't be allowed to fire them, etc. Liberals believe in a certain notion of human liberation from entrenched dogma, prejudice, and tradition, but this isn't the same as hostility to state action, even in the sex-and-gender sphere.