Mike Jenvey,
Exactly where have you been 20 months?
Surely, no rash decision on shoot down orders will be made if a 747 is commandeered at 50W, but if clear evidence is at hand with an aircraft near any major east coast city, or many military and nuke plants, things will get very ugly very quickly.
Bureaucratic paperwork snafus are probably not going to be a problem if these radical islamic scumbags try it again. On 9/11, some unarmed interceptors briefed how they might have to ram an aircraft after what happened in the morning. Waiting for an aircraft to land to check on political viewpoints isn't likely to be high on the list if a 400,000lb aircraft is near any potential targets.
Here is a quote you would never hear as an aircraft is diving for a landing out of FL200 as the attackers start to successfully breach the door. CA:"I say First Officer, thank heavens with all that is going on, we don't have to worry about shooting a gun at those misguided chaps breaking through the door behind us!"
The world is a messy place, carry a mop.