If you’re asking about the legality - it is probably legal since companies build in a lot of rights for themselves into their terms of service. It’s not fair but every company does it unfortunately. It needs regulations to be fixed.

Personally I am not a fan of bans on users, especially from social media, since social media is the only meaningful way to exercise freedom of speech these days. But we need to classify them as utilities or common carriers to have better protections.