Try frequenting any right-wing social media circle as a liberal and tell me how that theory holds up for you. Just because the landlords of the platforms are almost 100% left-leaning doesn't mean that right-wingers aren't totalitarian and censorship happy in the few little fiefdoms and sub-groups they control... because they absolutely are.
People can decide what is right for themselves— you don’t get to decide for them. They can decide not to associate with you and you cannot force them to do so because, you know, freedom. And you can voice your opinion about their decision on any platform that would tolerate you.
So first of all they broke the rules of Reddit over and over. Is breaking agreed upon rules free speech? Trump specifically and Republicans, conservatives, and Trump supporters in general, try limit liberal political ideas all of the time.