That’s true to some extent. I don’t agree with hard censorship like that, but there is also the risk of getting astroturfed and brigaded like reddit, which had a clear example as far back as 2013 where Eglin Air Force Base, FL showed up as “most addicted city”. The goal of censorship is to give your own opinions more space, so I’m not exactly upset if other instances are moderated in a different way when there are plenty of other instances moderated in a different way. The fediverse offers plenty of space.
Who is the OAuth provider in this case? The instance you sign up on? That’s already the case.