What an terrible accident.
Sounds like he prepped the victim into the litter kit and was already to be winched when he slipped or fell or stumbled from a rocky outcrop then swung accross the canyon and smashed into the cliff face absorbing the whole weight of the patient and the litter.
Crew lowered them both to the ground then couldn't get a response to clear to winch so cut the cable.
I reckon I would have gone to hell with it and just steady steady eased them both out and away to a suitable landing site.
Easy to say from my armchair though.