As POWs that is not necessary... a military tribunal and adjudication is sufficient.
And btw, I seem to recall we did some Nuremburg trials after a war. What was the legal basis for that? Thin air!
"Which is to say, the republics of Afghanistan and of Iraq, both functioning democracies with legal systems, should be eventually given full custody of these prisoners along with their legal dossiers, to give them appropriate trials."
Practically none of these prisoners are related to Iraq.
Most were captured in Afghanistan, but not just there - a Yemenese in Pakistan, crimes against us. Where do you send them? Send them to those countries and the whiners would have some reason to oppose that too.
The whiners are going to whine no matter what you do.
The best course is to simply ignore them.
It gets dicier if the courts start ordering you to release people who are going to go out there and murder American soldiers again.
If I were President, I would simply say "No" and establish an Executive veto over judicial opinions relating to command decisions in wartime.
But I already know from the Schiavo case that this President is not made of the right stuff to do that.