I'm not who you are responding to, but I think it is a different scenario.

HN has a very specific and limited topic range that is allowed and documented. There is some subjective things in what is allowed, but it is generally understood. People are not complaining about that. Nobody is suggesting HN should allow general sports news for example.

Twitter on the other hand is a general forum and so it should allow a broad amount of topics. If Twitter was a specific and targeted platform for cat pictures nobody would have an issue if they banned politics.

This is not even about the topics. HN has very clear moderation rules about tone of comments for example, rules against astro-turfing, rules about accusations of astro-turfing, and many others. Comments have to be substantive, otherwise they are voted down. Comments must not encourage flame-bait, otherwise they are removed.

HN is very highly moderated and you could even say tone-policed, and that is a major part of why many of us here like it.

Even Hacker News restricts abusive behavior, whether or not it's technically on topic. There are limits above and beyond an acceptable range of topics. Maybe I could get away with more here than Twitter, but not all behavior is permitted.

A lot of people here on HN are anti free speech.