I think they left two that didnt raised their hands but agreed with the Rick stating how they control council simply beacouse they needed such a guys to be still in some sort of control.
When you want to be in control you dont eliminate everyone but you eliminate most of them those that stays will fear you.
One way or another this Morty is super inteliggent and the scene where 4 school mates are getting mega seeds might indicate on how Evil Morty will get regular mortys inteligent as well