People aren’t obliged to listen to it but they have no right to prevent other people from seeing or hearing it unless it's stuffs like hate speech and racism
So, you're saying that if I have a conversation with my friend, and I don't let you listen in, THAT'S censorship? You have a problem with not being able to invade my privacy?
Sorry you got kicked out of whatever cool kids club it was, but you were not censored.
People are unable see content from other people that their instance has defederated with. (Yes, you can have an account on multiple instances, but that kind of defeats the point of federation.)
So, the inconvenience of having to go from one openly available source of information to ANOTHER openly available source of information, is the same as an authority figure preventing someone from speaking their own opinions?
That's like complaining about not being able to talk to your buddy across the street because you don't want to walk over there. God damn city put this street here and it's standing between me and my conversation!!!
Freedom of speech almost always comes with freedom of association. The thing that many people miss is that freedom of association also allows you to choose NOT to associate with someone just as freedom of religion includes freedom FROM religion. The instances choosing to defederated from the trolls are exercising their right to be free from association with the trolls. No one is stopping the trolls from spewing their nonsense or stopping anyone who wants to listen from listening.