Maybe there WAS a flight attendant in there with the co-pilot. And she was the terrorist. Stab the co-pilot, lock the door, pilot the plane into the ground.
That could be as well!
Good theory for the cockpit personnel problem.
If that's the cse, though, why then turn off the cellphone repeaters and ground phone comms? Possible answer - to buy time, and prevent from being shot down by the Mirages?
Problem with that - time is only important if you're aiming for a target, like a city. And why wouldn't you, if you're a Muslim terrorist? But apparently the goal was just a long, slow descent into the mountains. Doesn't sound like a terrorist target.