Regarding no damage to rotor blades. A far from definitive but intriguing thought;
Helicopter instructor praised for quick actions - National - NZ Herald News
Link to an article with details of an accident where a composite blade set struck the ground. It's not safe to assume that it was at rpm for flight (530rpm is 100%). Even at 80%, 424 rpm should be enough to produce significant damage.
There are differences, terrain, rod, aod, inertia and many others, but my assumption was also originally that intact blades indicate no rotational forces, but.....