can it have anything to do with safe min autorotative air speed
Nup,
Recommended is 65 knots, not as easy is 53 knots, specially on a hot day and heavy doing a standard - 1 flare.- 2.pitch pull - 3 level and cushion - and fixed attitude, quite safe as low as 35 knots, don't miss the pull. That done in the cool is easier on the nerves
Sounds like Robinson need to take a closer look at their advice and reference it to the real world.
Yup.