From a libertarian standpoint, the government regulating "neutrality" is a nightmare.

Should Hacker News be required to treat all links the same? If not, exactly how do you think a government "neutrality" mandate would work?

Because such a mandate means that if the HN moderators are a little biased, the whole shebang would become liable for any defamatory comments posted here. That's a government-mandated sword of Damocles hanging over every single moderation decision made here.