The engine was heard to quit before the crash. Spatial disorientation means you don't know which way is up. It doesn't mean you reach out and turn off the engine because you can't see where you're going.

The oldtime pilots were properly prepared with an artificial horizon created by the level of liquid in their always-handy whiskey bottle. If the top surface of the liquid was parallel to the bottom of the upright bottle, they were flying straight and level. They may have been flying smack into the side of a mountain, but they were going straight and level while doing it. If the bottle itself was spinning crazily on the floor, ceiling or doorframe of the cockpit, they had a serious problem that probably wouldn't last very long.

The site you indicated said "...approximately 40% of the NTSB fatal general aviation accident reports list continuation of flight into conditions for which the pilot was not qualified as either a contributing or proximate cause." [italics are mine]

That's a fancy way of calling it "Death by stupidity, pilot style".

'Tis a pity, though, that we shall never heard the results from the FFA.

Sue