“Destination PAKISTAN?”
Doubtful. To get to Pakistan on the fuel load you’d have to fly over India and the Indians would see you. Not enough fuel to go around. For the same reason, the plane didn’t fly four hours north. While the Vietnamese might not have very good radar coverage, China certainly does and would have seen the plane. Same for Taiwan and Japan on the original heading.
I thought of North Korea as a possibility but discarded that for the same reasons you mentioned plus warships of multiple nations and we damn well know for certain that country is under continous satellite observation.
Plus the Chinese would be really pissed at fat Kim :)