As for incapacitation after decompression, the useful time after such at 30,000 feet varies between 20 and 60 seconds, depending upon the individual. Surely enough time for the pilots to don their O2 masks. That they didn't suggests a slow decompression no one detected and that somehow failed to alert the pilots before they passed out. Hypoxia sets in with a feeling of warmth and euphoria for most.
Impossible so called "creeping" alerts are part of the pressurization fail safe, alarms would have indicated this situation to the pilots long before the situation required breathing apparatus to remain conscious