Maybe the disconnect is what is meant by open market. You might actually be complaining that people have too much choice and are free to start an instance, using their own resources and choose to disassociate from some others users. If someone sets up a roadside stand and lets their friends sell things there but refuses to let a friend of a friend sell his swastika stickers there, that isn’t censorship if the guy is allowed to open his open stand. It’s just not being overly helpful. If no one wants to go to swastika guy’s stand, and everyone makes fun of him, or even discourages other people from going there, that isn’t censorship either. It’s only censorship if he isn’t allowed to set up his own stand by someone in charge of that sort of thing.

What it sounds like you want isn’t a censorship-free platform, but a platform that is restricted from not choosing to give everyone the exact same voice. That may sound more fair to you, but when it costs person A money to facilitate person B’s access, and you don’t allow person A the choice to opt out of that (basically raising the bar for person A to participate), you’re actually restricting A instead of being fair to B.

In the case where person A is actually a public resource, that’s where it becomes censorship to block person B’s access, because then it’s a position of authority determining who gets to say what. But when person A is a regular guy, hog-tying him into helping person B blather about something hateful, or even just annoying, to person A is actually infringing on rights instead of promoting them.