Witnesses will undoubtedly be killed long before the time when the prosecution will be able to bring these assholes to trial.
Does anyone think that Al Queda has more moral convictions than the Mafia?
Does anyone remember how for 40 years in New York City you couldn't convict a Mafia kingpin of jaywalking, much less murder? How many potential witnesses disappeared before they were able to be called to the stand? Does anyone think that won't happen here with these terrorists?
I didn't leave it out, I just put down what immediately came to mind.
You are right, of course.
Other thoughts are the venue of the trial
Interrogation methodology
Revealing government intelligence gathering techniques.
I'm sure an attorney could come up with a few dozen.