Thanks. Agreed.
The question is really how and who.
I would take a good look at a stewardess who posted a picture of her wading out of water dragging her flight bag. That is a little beyond weird.
As for the pilot being the bad guy....maybe.
But there are several cases of pilots who intentionally crashed airliners and none of them used a bomb.
My guess is that it was a person who had no control over the aircraft so a bomb was required.
Good point in your last sentence. Bomb placed in the rear of the cockpit, under a jump seat or something which also impacted bathroom. Ground crew a possibility, anyone with access to cockpit. Right side cockpit windows getting blown out took a brunt of the explosion as well as disabling flight controls.