You make some very valid points chuks. I see those single engine/single pilot t-props like the Malibou, the Pilatus and the TBM as today's version of the Beech Bonanza. The Bonanza wasn't called the doctor/lawyer killer for nothing. It was for it's time an expensive high performance single, usually owned by a professional alpha male type, not prone to taking advice from many. Checklist? We doan need no steenkin' checklist.
By some reports the current victim had 5000 hours on the TBM. If this was indeed so, and not a typo, then he should have been more aware than most of the inherent danger of loss of pressurization and the use of supplemental oxygen.