The hypoxia theory is very plausible. But would not the pilots recover somewhat as the plane descended below 14,000 feet or so? Would the 5 to 6 minutes with low oxygen be sufficient to actually completely incapacitate all on board even below 10,000 feet as opposed to just making them temporarily unconscious down to that height?
If there is a
total decompression at 38K', you are not on Oxygen, and take >5 minutes to get below ~25K', your recovery options are not looking too good. Ever
(I think 3mins is the quoted figure where permanent damage becomes a possibility - many will last longer IIRC)