This'll make your eyes water;
Add a bit of rotation a sniff of wind and stand well back!!!
Ok so a bit of an extreme case the old Chinook, but I would hazard a guess that with a slow-med rotation speed and a reasonable wind, the blade sail for even something like the Lynx/135 types would still be a good couple or three feet.
Bearing in mind the original post relates to the GNAA which will be operating in, I would suspect, uneven ground a lot of the time, no matter which type of machine they use, the risk of a blade coming down to head/'arm holding drip up' height, would be reasonably high. Definitely high enough of a risk to warrant mention in a brief, it even if they had a 135!
Slow rotor speed + incoming crew/pax = high risk of mess!