None of us knows. The truth will most likely never come out.... until it is in the best interests of someone, or a group of people, for the facts to emerge.
If that plane had been fueled sufficient for it to reach Beijing, it would have been able to reach anywhere in China; the Arabian Gulf; any island in the Indian Ocean; anywhere in the area of Indonesia, the Western Pacific, most of the Australian mainland.
Someone is hiding something? Who knows?