Things like this are not immediately appealable. He’d have to wait until the case is over. Delay of months at least. Pardon now, I don’t care nor will any rational person, it’s obviously political
Actually, you can appeal things that have immediate damage potential. This meets that definition.
Yesterday.
Flynn Defense Files Motion in Opposition to Amicus Briefs
https://theconservativetreehouse.com/2020/05/12/flynn-defense-files-motion-in-opposition-to-amicus-briefs
There is no objection to this motion so this Sullivan fellow will have at most one week to rule on the motion. When he denies the motion, the next day at the latest, Attorney Sydney Powell will file an emergency appeal in the DC Court of Appeals which has had a makeover during the Trump years.
Oh, I believe it is. Powell is extremely competent. I suspect she will file to have him removed at best, smacked down at the least.
I wouldn't bet against Barr and Powell.