Spammers or disrupters coming back is one issue, but that there is no way to remove someone from a JOT group chat is the bigger problem.  Edit Participants doesn't remove them nor does suspending or deleting the member.  Nor can moderators delete JOT messages.  So the current situation is only Admin can delete messages in JOT and no one can remove a Spammer from a JOT conversation.   This was supposedly going to be fixed in Sept 2019, but several updates have not fixed it.