C'mon, now - there's a difference between making war and prosecuting criminals. If you want to arrest this guy and prosecute him like a criminal, follow the rules that are in place to do so. If you want to treat him like a prisoner of war, then do that. But don't try to have it both ways.
In 1942, would you have turned loose a 25 year old German "student" with portraits of Adolf hitler and rabidly pro-Nazi literature in his house who had very close contacts with proven Gestapo and SS agents who had just killed 3,000 Americans?
Just asking.
How about after we lose a city and 100,000 citizens after the next attack? Will you reconsider then?
How about after a million dead?