lonewolf - your understanding of the implication is correct - i.e. most of the rotor inertia may have been "used" by the time of impact, hence very low rotor speed at the final stage.
Re inertia - most twin engine helicopters have low inertia rotor systems, as they're optimised for powered flight. As it's normal for such machines to stay powered in the event of a (very rare) single engine failure, the rotor systems will autorotate, but Nr tends to be a challenge to control (in a modern twin anyway). A single, such as B206, will have a rotor system that has a good deal of inertia should the (normally reliable) engine fail, and makes it relatively safe and easy to get into auto. I'm sure this debate has been debated & discussed in greater detail in rotorheads by experts such as Nick Lappos.
RotorRPM - to clarify, the tail rotor area, fin & horizontal stabilisers appear largely intact and a separate photo showing the fenestron itself, i.e. the fan, appeared mostly full of blades. I say "appeared" as I felt the angle was difficult to see if there were blades attached to the bit out of view.