Rather than all 3 on the pass being involved in a fist fight/murder I suspect their knuckle injuries, which only they had across both hands (Yuri K was the only other one with knuckle injuries, but only to his right hand), were likely caused by them crawling up the pass, avoiding frostbite to their numbing fingers by walking on their fists, and in the case of Igor who had no shoes, possibly attempting to save his toes by walking on his knees (only he had kneecap injuries).
You think they were crawling back to the tent? Why not just huddle together?
I would suggest because they needed sustenance, food, having burned off all their calories in the fight against the cold. They have shelter and water but not the third thing they need to survive, and their blood sugars would be dangerously low in hypothermic terms. Additionally the effects of hypothermia may have affected their decision-making process, so they set off too soon.
Their plan, presumably, would be to retrieve the food, eat something at the tent, drag the rest down the pass, hole up in the den they covered with evergreen fir branches and snow, then either await rescue or make their way back to the labaz.
As regards the other 4, I'm now convinced they died of injuries/hypothermia, and these final 3 slid them into the ravine, all heads one end, and covered them with snow from the bank, to hide them from a military helicopter buzzing the area that night, possibly out looking for escapees, the same helicopter later sees these 3 on the pass the next day, lands and turns the bodies, explaining the movement post mortem.
I could well be wrong, but that is my logic - everything is about hypothermia, their behaviour, decisions, injuries, resuscitation attempts, burns during agonal stages etc - and these 3 were the strongest.