What makes anyone think that a suicidal terrorist is just going to sit there and watch the aircraft land itself. They're going to pull circut breakers, tear up wiring bundles, start fires, etc to crash the aircraft.
The only way you're going to stop it is to KILL the terrorist on the spot and not surrender command of the aircraft.
But since our government doesn't trust us with firearms, they've decided to shoot us down instead. Bizarre.