The crew had no idea that these people were this evil. They probably assumed that the terrorists would demand to go to Cuba, or make some public statement demanding the release of the WTC bombers. You can't judge the actions of the crew without knowing any of the facts.
Believe me, I am not judging them. They had no way of knowing.
WTC2 has changed everyhing.
Anybody who tries to hijack an airliner in the future will be attacked and dismembered by the passengers before he can walk ten feet.