Think of it like your house. You can ask people to leave if they say something you find offensive. That is not infringing on their free speech.
If the owner of a shopping mall wants to ban the word banana, they can ask anyone who says it to leave. That is also not infringing on their free speech. That’s because shopping malls are not owned and operated by the government.
Bluesky has 20x the user base (and the gap is growing wider every day).