The complaint (.pdf) filed by Kucinich is simple and straightforward. He alleges that he had a binding contract with MSNBC once they offered and he accepted the terms of his participation in the debate, and that MSNBC's refusal to allow him to participate constitutes a breach of that contract. He also alleges that his exclusion violates the mandates of Section 315 of the Communications Act, which requires broadcasters—who operate the public airways, i.e., airways which are public, not private, property—"to operate in the public interest and to afford reasonable opportunity for the discussion of conflicting views of public importance."
Nobody can opine meaningfully on the propriety of the court decision here without first knowing about, and then analyzing and resolving, those legal claims. That's how the law, when properly applied, works. You don't get to pick which outcome you think is most desirable or "fairest" in some vague philosophical sense and then, based on those preferences, decide if the court correctly adjudicated the questions before it. A court adhering to the rule of law, by definition, applies the law and legal principles. Self-evidently, to know if the court acted properly, a basic knowledge of those laws and legal principles—at minimum—is first necessary.
The rest is too long to blockquote, because, uh, it's a Glenn Greenwald post. But his point is that conservatives who wanted to mock Kucinich attacked his lawsuit as frivolous without applying any sort of rigor or understanding of the law. In their defense, Kucinich likes to file frivolous lawsuits. He's being challenged in his congressional district by a couple of Democrats who want their congressman to behave more like a congressman, and one of them filmed himself looking for Dennis at a few of his Ohio offices—a campaign gambit that goes back at least to 1992, when Russ Feingold did it to his opponent.
Cimperman entered Kucinich's office while a campaign worker taped him dropping off one of the posters at the front desk.
"I walked in, asked for Dennis, dropped off the poster and walked out, all in one big motion," Cimperman said. "I was polite and in there 20 seconds."
But Kucinich, who is seeking a seventh term to Congress while aggressively running for president, believed the incident violated the privacy of constituents visiting his office.
"The people must have some assurances that their government does not allow individuals to enter the premises and film them while they are seeking federal assistance," Kucinich's office wrote in a letter to the Federal Protective Service. An agency under the U.S. Department of Homeland Security, it has law enforcement jurisdiction over government offices.
That's the same DHS that Kucinich votes against funding.
As with the lawsuit that Clinton allies filed to break up Nevada caucus sites, Kucinich's suit against NBC was an electioneering stunt that failed. Most of these heat-of-the-moment legal barrages are.
Headline explained here.