A commotion would have been an indication of terrorist activity. Passengers these days know not to submit to terrorists' demands. If there had been any indication of terrorism, you would have had passengers restraining the terrorists, beating on the doors of the cockpit, calling for help on their cell phones, and so on. The fact that there is no evidence any of this happened indicates that it was likely mechanical failure or pilot error.

Also, does anyone know how common this "stolen passport" situation is? On a typical day, worldwide, how many people board aircraft with stolen passports?