That's why it went up to 45,000 feet.
The cabin was depressurized when the captain said 'good night' and turned out the lights. All on board lost consciousness and when he brought it up to 45,000 feet, they all died within minutes.
That is why their cellphones continued to ring in their pockets and purses when relatives called. They were all dead. There would be no resistance nor counterattack.
They wanted that plane - that was the prize.
They have it as it did not go into the water, but flew for 7 hours. It is now in Pakistan being fitted for its final mission.
Also, this flight was an overnight red eye flight to Bejing, so most of the passengers were probably asleep or dozing already.
Less resistance so they won’t fight back like flight 93.
Sounds very plausible and well thought out.
Pure evil if that is what they did. How did they know the plane would not break apart when it hit 45,000 ft or that their oxygen would work on themselves.
Your theory is too complicated to be pulled off without dedicated operatives and government support.
It is most likely a case of Sudden Jihad Syndrome.