Tinfoil hat on...
It was hijacked by Chinese muslim separatists from Xinjiang from western China. The plane was intended to be flown to and landed there. Possibly for use later as ‘bomb’ to attack government target or to attract attention to the cause, etc. Did it get there?
Doubtful, it could evade Chinese air defense detection. The jet was possibly shot down for not having a transponder on - or perhaps the Chinese figured out the plot, and a decision was made to shoot it down to spare the Chinese the trouble of dealing with terrorists, negotiations, giving more notoriety to the movement, etc.
The Chinese wanted to deflect attention from their possible involvement and knowledge, so they offered satellite photos placing ‘wreckage’ in the waters near Malaysia and ‘seismic’ events - all in an effort to keep attention away from China.
So I guess if some of the stolen passport guys were Chinese, well it could still fly.
What I like about it is that is where it looks like the flight path is headed. Xiniang or whatever.