If the Bills had a healthy Watkins, McCoy, Woods, etc and Tyrod was still struggling the way he has been, then I might also be on board with giving Manuel another shot.
But putting EJ in there right now would accomplish nothing but create continuity problems, and do so with only a minimal chance of seeing any improvement in the offense.
I think it's just too much risk without enough reward.
As for Cardale, let's just say that he is nowhere near ready to manage an NFL offense, even one in it's simplest, most basic form.