You're reading too much Tom Clancy novels.
If this really is so, there will be huge political/diplomatic repercussions between Iran and China. Kidnapping people just to get an airplane? Well, Iran could much more easily set up a front company that dry-leases any airplane, and go from there...
My own little pet theory is that the FO has a grudge against MH
and/or the captain. He kills the captain which he envies for his enthusiasm/success and switches off the transponders. Knowing that he'll be apprehended if he lands in PEK
or somewhere else, he flies to Sumatra, for two reasons: Less ATC supervision, and more time to think about a solution. Then, as it appears to him that he'll end up jobless (and end up in a mental asylum or prison) anyway, he decides for a suicide, taking all pax and F/As with him.
As it is night and the moving maps on the IFE are switched off, nobody gets suspicious. In a fast, circling descent, he approaches the surface of the sea, slamming head-on into the water at several hundred knots, leaving next to no debris.
Okay, now I admit to reading Tom Clancy novels.
[Edited 2014-03-11 11:31:09]