Maybe we've had it wrong, instead of Trump being completely blocked from Twitter, wouldn't "POTUS twitter removal" only mean that the name on https://twitter.com/potus switches to Joe Biden, but https://twitter.com/realdonaldtrump stays up?
I don't remember the words "Trump twitter removal", but only POTUS. Maybe this only means the @potus account itself getting changed to Biden, since Twitter has control of this.
He doesnt use the @POTUS. He uses @realDonaldTrump
Don't forget...a user can delete their own account.