The only issue that I can find with this whole sorry affair is, since I've flown light/medium/some heavy twin-engine aircraft for many years, as a practical matter, on a turnaround, I was always careful to keep the engine running (if necessary) on the opposite side of the aircraft from where passengers embark/disembark for this exact reason.
One engine running keeps the air conditioning, lighting, avionics and other systems operating for a rapid departure, and shortens the pre-takeoff checklist considerably.......I never allowed the cabin door to be opened on the same side of the aircraft with a rotating prop.
It's tough enough to keep an eye on where ramp personnel are, and they are supposedly trained (or one would assume), let alone passengers........and on more than one occasion, I've seen ramp personnel nearly walk into a prop inadvertently.
doc