If that's true, and the pilots were hypoxic, I see no way they could have flown the route that has been reported. (I'm now phrasing everything hypothetically because so many things have been retracted!) We've discussed the possible turn-back to Palau Langkawi, but if that setting had been made, the crew almost certainly could have radioed a pan pan pan; and the aircraft would have circled PL until it ran out of fuel, rather than turning to the south. The plane would have also immediately dropped altitude to raise the oxygen level for the pax.

The number of mishaps (lack of pressurization, fire, etc) that are needed to explain the flight's path and lack of contact via radio + loss of ACARS + loss of transponder - yes, it could have been a perfect storm but the probability of all those failures occurring as they did is low enough that deliberate pilot action has a higher probability. Search for Palau Langkawi and you'll find many posts on this subject.