We moderate political threads, not for ideological reasons but in the hope of preserving HN as a place for civil, substantive discussion. Many views can be and are exchanged here, but when people post in a way that threatens the container itself, we moderate and/or ban them. The mandate of the community requires this.
Sometimes (well, frequently) this provokes an angry response from the moderated and/or banned user, who sees us as their enemy and accuses us of making decisions for ideological reasons. The thing is, though, this response arises in almost identical form regardless of the ideology that user favors. There are countless examples of people complaining about HN being biased in just the opposite way to how you see it. What these complaints have in common is not the politics they favor—they completely disagree on that—but the intense emotion with which they favor it. That's presumably the same emotion that motivates the inflammatory flamewar-style comments in the first place. This is the force that threatens the container and we all need to do the work of moderating it in ourselves so we can (a) hear each other and (b) not wreck the commons. If you want to do that work, you're welcome here.