Twitter is "about" advertising; everything else is incidental. Bans only happen if Twitter believes that doing so (a) gains users or (b) prevents users from leaving.

Hate speech, election meddling, threats of nuclear war - it all gets a free pass until it stops generating "impressions".

But they only do it because we (as a group) let them get away with it. If 30% of Twitter users left, the platform wouldn't last a week.