No, they can just decline the request.
Of course. But, if he's been canvassing the judges to see how they would vote on an en banc request, he might be betting they will take it and it would go his way.
On the other hand, if he's been instructed by people he owes favors to to play out the delaying hand as long as he can, then this is the thing to do, even if the Court operates properly. It takes time for them to refuse.
Then he'd probably get another 21 days to respond to the existing order (just as he had here).