Ahem, has anybody noticed, that the blades are upside down? The whole control linkage must have been ripped of.
I know that area. It isn't very steep and there isn't enough snow to slide on.
The perceived sliding action might come from not setting the helicopter down completely.
Now, if the controle linkage breakes, the blades would immediataly turn either up or down and break or bend in an instant. If they touch the ground, they would also stop immediately. That could explain the sudden stop, the bent mast and the intact tail boom. Weird. The accident report will be an interesting reading.
PS: And for all the Robinson bashers. Move on. Get it over with. There are other helicopters with worse accident statistics.