Quite right HG.
Interestingly a couple of the places I've hired from in the past, when I've had a passenger and taken the duals out and plonked 'em on the desk in the office the people have looked at me rather baffled.
But it's by far the best way to make sure there's no problems - and more comfortable for your passenger not having to keep themselves out of the way of the controls.
And if I ever do have anyone entering or leaving the machine with the engine running (instructor, examiner etc.) you can bet my left hand is holding the collective down and the throttle closed
