I think that since the POW in question is an American citizen, that the Administration should be required to present their evidence of Hamadi's complicity with the Taliban and Hamadi's attorneys should have the opportunity to challenge that evidence.
That sounds like treason. If he should be charged with anything, it should be treason. If treason can't be proved, then he should be treated as a POW.
I think the point is that there should be some kind of due process where the Administration must present the facts that an American citizen had taken up arms against this country, and the citizen in question has the ability to challenge the facts. Otherwise, the precedent is set for an Administration (not necessarily this one) to declare just about ANYONE an enemy combatant, whether or not they actually are, and they have no ability to defend themselves under the Constitution.
If the Administration makes it case, then hose the sumbitch.