I just saw a video that speculated 3 reasons. 1 was his political views, he's a big Trump supporter and most of the lacker room isnt so there was backstage heat, i don't believe that to be a reason at all. 2 is that a few weeks ago he "went into business for himself" during the segment with the midget wrestler impersonating Daniel Bryan, the guy wanted to do more than just be kicked once but Vince didn't like that idea, Cass punched him again after he was already down. 3 was that there was an incident on a flight, no word on what or when it was.