His argument isn't even very good. Like, did you not read the terms of service? They probably explicitly state they can remove you for any reason and you clicked "yeah, sure".

A much better argument is that twitter and youtube are shielded from legal liability from what people post on their sites due to section 230; that being the case, there should be a corresponding requirement for them to allow anyone to post anything so long as it's legal. If they want to play around with algorithms or monetization after that, I don't really care.