Russian hippies, bad drugs.
It was just a case of hypothermia delirium a subset of which is known as paradoxical undressing, sometimes the hypothermia screws up the hypothalamus and you start stripping, either because you "feel" unbearably hot, or it makes the clothing feel unbearably restrictive.
There's dozens of other documented cases of paradoxical undressing in other countries. And RKL is onto something, because most of them involve drugs or alcohol as contributing factors to the hypothermia.
The damage to the campsite was from an avalanche, (I'd sure as hell "rip my tent open from the inside to get out of there, or maybe the air-pressure just burst the tent...) that might have been the event that caused the hypothermia and the broken bones in the group in the first place, or perhaps it happened afterward and is what scattered the campsite around.
The one woman who lost her tongue probably did to a scavenging animal.
The radiation and "lights in the sky" part is just bull****, that got added onto the story urban-legend style.