To raise the bar so high, encourages US soldiers to kill terrorists, not capture them.
Protections of the constitution apply only to US citizens, not illegal combatants.
To have tried the mastermind of 9/11 in Manhatten, would have cost a billion dollars.
Military tribunals for captured spies, and others who are not unformed soldiers,
has precedence. Captured Nazi spies were given a military trial, and executed.