You could be right, but even in the world of psycho serial killers, this would be extremely out of the ordinary. Serial killers generally want to get their hands dirty, not sit in what amounts to a separate room while all his victims are elsewhere. They didn't even know they were in danger until the final seconds.
He could be crazy, but I still suspect a political motive and Islam is the dominant political movement that uses these tactics. We'll learn more in the coming days.
It’s also entirely possible that there was a sensor malfunction that caused the flight computer to put the aircraft into a controlled descent. They had reached their cruising altitude and the autopilot was most likely engaged. Without the flight data recorder it is impossible to know for sure, though. Jumping to the conclusion that this was an intentional act to down the aircraft seems very premature, given what is known. Then again, France has a vested interest in this being anything but another Airbus sensor failure related crash. At least two previous Airbus crashes have been attributed to sensors reporting false data to the fligth computer. One was a pitot tube that froze up and gave false airspeed information. The other was an angle of attack indicator which sent bogus data to the flight computer because it had been damaged by water that got in the sensor when the aircraft was washed. It later froze when the aircraft reached an altitude where the ambient temerpature was below freezing. In both incidences the flight computer lowered the nose. A low time pilot may very well have become disoriented and panicked when he realized he didn’t have control of the aircraft, even with the autopilot turned off. I know several pilots typed in the Airbus A320 and none of them like it because of the tendency of the flight computer to “adjust” the flight parameters, even with the autopilot off.
One or both