They weren't prevented from saying wrong things or even penalized for lying.

They were deplatformed. You don't have a first amendment right to use platforms as you like and those platforms have the same first amendment right you do to decide what is brought forward as emphasized by that platform.

Should the government be allowed to influence that and in what way is an interesting question but it is less the end users rights and more the platforms rights in question here.

Getting removed from the algorithm isn't censorship.