I'd be interested in your reasons for disagreeing albatross - for me the low Nr horn is a significant indicator of overpitching and asking for a collective pitch position that the engine can't provide enough power for.
SWP can lead to VRS but the fact they survived the impact would lead me to believe the RoD was not that of fully developed VRS.
I have not seen any video from inside the accident aircraft in Edson. Please post a link.
Also overpitching the collective to a position in your armpit is often a reaction to sudden, low level, VRS especially if the planet is fast approaching. This massive over-torque will lead to the low rotor horn and an accelerated rate of descent.