Ian... They "key" to this is not likely "reaction times" or "experience" etc. It is legal to fly to 65, but crucially as "multi-crew"
AFAIK. The 60 limit applies to single pilot operations... and is therefore likely medically based on the probability of incapacitation. I am presuming my fixed wing ideas above apply to rotary as well.
Given drivers have additional tests etc. at 70?, and these have presumably been justified / challenged, I would imagine the CAA have to draw the line somewhere. The case will no doubt determine whether 60 is judged appropriate...
NoD