[afraidfortherepublic]

He then takes public transportation back to JFK and boards the next flight to Saudi Arabia

Here's where your hypothesis falls apart. All flights in/out of NYC were grounded for days. I think this was accomplished by the hijackers themselves, or one of their compatriots that they left behind. Remember all of the Middle Easterners who suddenly fled the country in the week after the attack? And there would be no record of anyone who managed to cross either the Canadian or Mexican border on foot.

[MindBender26]

Commercial aircraft were grounded for 3 days and were flying again long before letters were mailed from Trenton.