Hard to buy that one guys description of why the plane all of a sudden dropped altitude and the propeller quit turning after engine failure.

True if they were gliding at near stall speed and turned to put wind at their tail, the plane could have stalled but I can't imagine an experienced pilot gliding near stall speed, and if you have any altitude at all which I assume they had, it takes very little time to push the nose over and recover from stall.

I have cut off my engine in flight before, and stalled the airplane to stop the propeller from turning, then I dived down at high rate of speed to restart the engine with wind pressure.