Nature does not need a reason, people do. Absense of evidence is not evidence of absense. This conspiracists fall back on. I prefer Occam's razor. Natural causes compounded by unfortunate circumstance seems right. I like the slab slip idea as the precipitating incident.
There is already countless evidence that forces other than nature kill. So we have the evidence. It is very clear that nature is the ineffective element in this event. No one on that slope, not even an amateur, dies of cold in just 6 hours. This is not possible. It takes at least 24 hours to die from the cold. By then it will already be daytime and the temperature will likely rise above 0 degrees. This will definitely save them. So hikers kill from any external factor, not from the cold. You still dream of saying nature, nature, nature...
In winter in the Northern Urals, 0 degrees is rather a very rare anomaly. Almost always minus temperatures. In addition, I assure you, the temperature on the slope can be very different from the temperature in the lowland near the stream. For example, on the slope the wind is -10, and near the stream -20 and no wind.
Зимой на Северном Урале 0 градусов это уже скорее очень редкая аномалия. Практически всегда минусовая температура. Кроме того, я вас уверяю, температура на склоне может сильно отличаться от температуры в низине у ручья. Например, на склоне ветер и -10, а у ручья -20 и без ветра.