The term ‘enemy combatant’ is not contained in the Constitution as a 5th Amendment exception, so we’re allowing the federal executive to create a self-determined, non-reviewable category of individuals who can be assasinated at will. We may like the result in this case, but it’s a very troublesome process, or lack thereof. It needs to be worked out.
There’s very strong evidence that this dude committed treason against America. Yes, he did not get a trial. Perhaps he should have been tried in absentia. Then upon conviction he would have been a legitimate target, based on the points you are bringing up.
I have to refresh my memory about John Walker Lindh, the dude who was fighting for the Taliban. Why exactly is he in prison? He’s an American citizen.
I think our laws need updating to deal with cases in which American citizens are the enemy.