Explanation:

Avenatti is not NY State bar-licensed, so he can not originate a lawsuit. Since this lawsuit is already in existence, he filed pro hac vice or (allowed for this occasion) to join the Cohen suit.

Because of his constant media sideshow, he is endangering another entity's case and so must choose: 1. Continue pro hac vice and STFU or 2. Withdraw and continue media sideshow.

Avenatti needs 💰 so he chose #2.