It seems that the environment around helicopters for the unaware can lead to brain overload and subsequent dysfunction.
Noise, expectation, excitement, uncertainty / fear, proximity to large fast rotating parts, exhaust gas smells, dust etc etc seems to overload normally sane people.
You can lecture them until you are blue in the face, but you just can't trust that any of it has been taken in.
Maybe pax need to be told that they will probably lose the plot? All ground crew I have worked with have been warned to treat all pax as sheep regardless of who they are as they will do dumb !!!! in a millisecond as they are basically unconscious.
If you have the slightest uncertainty or any reservation about the experience of the pax - shut down and remember it applies whether loading or unloading .