I understand a thin layer of ice formed beneath Rustem when he fell to earth. The ice, a result of body heat dissipation. This means that Rustem and others were returning to the tent alive. Rustem was not placed there as a corpse, but rather, he fell there and expired. Later, fresh snow covered him up until he was discovered.
The formation of ice under his body implies two things. First, Rustem and the others were trying to regain the tent. Secondly, tent at 880 was pitched just where it was found by rescuers and not relocated to there from elsewhere.
It follows that there was something worth getting from the tent. If the tent was cut to shreds during their departure, belongings and supplies could be scattered and lost in blowing snow. The actual condition of the tent and its contents were found intact. The much discussed damage to the tent then was largely a product of rescue attempts to breach the frozen canvas and the crude retrieval of the camp property for later inspection. The slabs of snow on the tent as photographed by the rescue party support the slab slip hypothesis which is the current official conclusion.
Again, Rustem was not chased down by wolves, they did not feed on him. No bullet holes were found on him. The decision to regain the tent was a deliberate conscious choice. We may surmise it was not a wise decision. Hypothermia clouds judgement. By extension, the decision to leave the tent was in all probability also a conscious voluntary decision by all. Semyon's meltdown makes a compelling theater. The trouble is, if he killed everybody else how could he explaini it away? Soviet authorities would get the truth out of him. If he survived, ran and hid , he could not stay missing forever they can count to nine, yes?. Too, he would have raided the cache which would be hard to explain
away to investigators. Finally, if he forced everyone out of the tent by threatening them with an ice pick, why did he abandon his weapon when he descended to the forest to complete his crime?
For me, Rustem's ice effectively rules out an elaborate plot and fringe theories. A snow slip and hypothermia are mundane, but Occam's Razor is remembered for a reason.