You have to choose the courts review your case? Did the Unabomber choose to come in for redress? Did Eric Rudolph? You're not entitled to Due Process only if you "express willingness," you're entitled regardless. They should have determined the proper forum to try him, complete with review if necessary, in absentia if necessary even. If they could craft a memo to give themselves legal cover then I'm sure they could have devised a way to try him by military tribunal.