Obviously, I have not read every post. But could someone tell what evidence has come to light that has so many pointing the finger at one of the pilots? I've seen nothing that leads me to believe one of the pilots (to descend into the vernacular) 'went rogue'. In fact, the erratic altitude readouts not long after the diversion would appear to give some credence to either a struggle for control or someone at the controls having difficulty flying the aircraft.
Anyone who has flown as a line pilot or cabin crew for any length of time would not find it difficult to believe that, despite locked doors and security procedures in place since 2001, (and particularly given the position of the toilets on the 777), intruders could gain access to the cockpit with relative ease.
Neither should anyone be surprised that there might be someone out here with the engineering (and perhaps flying) expertise apparently displayed here whose skills could not either be bought - or just as likely, made available willingly by a committed believer of a cause.