Also, remember, the co-pilot was breathing normally and did not utter a word during these 8 minutes. If he was having any kind of medical issue or panicked or trying to deal with an emergency, or anything, he would have made a sound, said something, some kind of vocal reaction. He pressumably didn't have any vocalization of any sort, other than normal breathing, even though there was banging on the door, passenger cries, plane descenting, etc. This alone pretty much rules out any alternative explanations, IMO.