He’s probably hoping the full court will overrule the panel.
DOJ should be dropping rockets on Sullivan on a near daily basis until he surrenders. They are not.
He likely would if he could, unfortunately (for him) only a party to the case "defense or prosecution" can file an appeal, and because both parties want the case dropped neither are going to appeal. The Judge can't "appeal" as he is (supposedly) a neutral party so doesn't have the standing to appeal anything.
Now Judge Sullivan did try to "backdoor" an appeal by appointing a fellow left wing judge as a supposedly "unbiased" 3rd party (who of course issued a finding saying that the Flynn case should continue). But that went nowhere at the appeals court because they rightfully said a 3rd party brought into the case by a Judge as no more right to appeal than the Judge himself.