There isn’t really a single “fediverse” that decides what’s “allowed”. What your fediverse is depends on where your account is and who they’re federated with. You’re perfectly free to say whatever you want on your own instance and talk to the other people on instances willing to federate with you. The thing is, being mean to people who have done nothing to harm you tends to make you pretty unpopular and make people not want to interact with you, that’s why instances that encourage that tend to not be federated with very many popular instances.
What? People are allowed to avoid people they have serious disagreements with? You have every right to have whatever unkind opinions you want to have, but that doesn’t mean anyone is required to listen to you or like you. You’re never going to be liked by everyone in the world, but if you can hardly find anyone willing to be around you, it’s probably time to do some self refelction