Sullivan is not a party to the case. Therefore, he has no standing to ask for an en banc review, nor to appeal to SCOTUS.
And the cherry on top is that he is asserting that the Court (him in this case, but in principle any other Federal judge) has the RIGHT to order an adversarial proceeding after the adversaries have withdrawn, with new adversaries chosen by him alone.
Because the government is so out of control, it would not surprise me if the DC circuit endorsed such a notion, but it obviously smashes down the wall separating judicial from executive functions, and could be considered part of the coup because it could only happen with President Trump in the White House.