Government colluding with private corporations to violate peoples rights is pretty much the recipe for fascism.
That's the loophole that allows it to work.
Government is restrained by the constitution, so they enlist private corporations to do the dirty work. By extortion, bribes, or downright capture.
Did the government force Twitter to ban Trump, etc? No, so that's an invalid argument. Twitter chose to do so from the feedback of their users. I don't see an issue with this.