That is the market deciding. Twitter's market is liberals and leftists, so twitter changes the platform based on their demand. If you don't like this, then you don't like free markets.
Many HN posters: "We love free markets, every company should follow their own rules and do what they want"
Company bans violent and insurrectionist speech as is their legal right
Many HN posters: "No, not like that!"
If an American platform hosts public officials who use that platform for political purposes, then it should follow that all American citizens should have access to engage, comment and react.
Public officials relying on private platforms for public policy purposes, fundraising etc seems absurd and grotesquely undemocratic.
Strongly agree on public officials using private platforms for policy, but they must have seen something attractive about it. Free people and whatnot...