This discussion is (largely) silly and completely beside the point.
Are there really clubs whose flying order books do not include "no running changes" (with the possible exception of the instructor getting out for a change from dual to solo)?
Do they really manage to leave their customers with the idea that following some not-understood engine management procedure takes precedence over safety? What's worse, destroying an engine or destroying a person?
Should it not occur to a pilot that if someone needs to get out and the engine can't be shut down yet (not matter how falsely that belief is held) the correct procedure is to sit there and wait until the engine can be shut down?
Are there really any pilots whose passenger briefing does not include fairly explicit briefings as to why the passenger should not go anywhere near a propellor?
I'm sure I've missed some, so there must be more than just four reasons why such accidents shouldn't happen.