It isn’t about having something to say and being heard, it’s about having nothing to say and forcing people who don’t want to listen to listen. They’re just pissed off because the fediverse gives people the ability to exercise their right to freedom NOT to associate with them. Trolling isn’t fun without a captive audience to torture.
https://gizmodo.com/online-trolls-actually-just-assholes-all-the-time-stud-1847575210
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.
No one is preventing anyone from hearing it. You are free to create an account on those instances and listen to them if you want.
Working for the federal government in Canada I learned that following the process is far more important than getting anything done.