I subscribe to multiple high-sub-count YouTube channels that post videos about guns on a regular basis. Are you referring to their rules about violent/explicit content? That is absolutely not a subject matter ban like 'you can't discuss guns' and the facts don't support a claim that they ban guns.
YouTube's rules enforcement for videos is notoriously bad and has been forever, but that doesn't change their actual policies.
Enforcement is more pertinent than policy. If their policy allows for such videos, but in practice removes them, it doesn't really matter what their policy is.
YouTube's rules enforcement for videos is notoriously bad and has been forever, but that doesn't change their actual policies.