Our demands are NOT to fly plane into any target but rather hold flight as ransom...
And, of course, everyone would believe that was the actual goal because the govt. considers hijackers to be honorable people who always tell the truth about their true goals.
The point being that the govt. can't afford to guess wrong. If the plane is taken over it's going to be shot down. There's simply not any room for error. 300 dead and a destroyed airliner is a pretty ugly prospect, but not compared to 2500 dead and potentially hundreds of millions or more in property losses.
It's a new world after 9/11 in terms of how hijackings will be dealt with. If a plane is hijacked and the passengers & crew can't regain control of the airplane very rapidly then everyone aboard will die when the plane is shot down.
In light of that reality, if every innocent person aboard except for the pilot is killed in the process of successfully regaining control of the aircraft then it's a win when one compares that outcome to the outcome of not regaining control before the government acts.
And if everyone dies in the process of attempting to regain control it's no worse than what will happen if the govt. has to act first.