More likely they considered it and determined it to be a remote enough chance relative to a passenger being the hijacker that keeping the door locked was the better default. A LOT of things have to happen correctly (or incorrectly depending on perspective) for a fully trained pilot to decide to and successfully attack the other pilot and take down the aircraft.
More likely they considered it and determined it to be a remote enough chance relative to a passenger being the hijacker that keeping the door locked was the better default. A LOT of things have to happen correctly (or incorrectly depending on perspective) for a fully trained pilot to decide to and successfully attack the other pilot and take down the aircraft.