eurocentric, I don't think the weather is a major factor in terms of the explanation, because we know it must have been quite cold and windy. If it was outrageously cold and windy, they would not have been able to secure the tent, get down to the treeline without apparent problem, rip off a whole lot of branches, start a robust campfire, dig out the "den," and then one of them got about halfway back up to the tent after all that (Zina), not wearing proper clothing (at least 7 of them).
DAXXY, I think the coats and boots were either frozen or they didn't want to risk those items getting frozen, which is why they secured the tent the way they did. Rather, it was just a "bad call," thinking it would be highly likely they'd survive if they could just get to the treeline and start a robust fire. I'd be curious to know if the "den" was started right away or only after the fire seemed to be a bad idea. It's certainly possible the idea was for the two guys who were better dressed to dig out the "den" while the others started, then huddled round the fire to warm up. Then they would all go to the "den," lie on a bed of branches, and huddle together until sunrise. Zina saw at least one Yuri die, then was angry or upset, and decided to go back to the tent, thinking Igor didn't know what he was doing. Then Slobodin went after her, hit his head, and lie unconsious. Then Igor goes after her, but hypothermia sets in (and I think they must have been too tired and sweated up for them to be able to get back to the tent, walking directly into the strong winds). I do think that not taking the blankets with them was clearly strange, but if a reconstruction was done, perhaps we would see that it was too windy, and also they couldn't do all that work with blankets wrapped around them. Or they didn't want the blankets to get frozen. There is no way to know what the thought process was, but plenty of people have had the wrong idea about how to survive in the wild, especially in an area they've never visited before under harsh weather conditions, so I don't think it makes sense to say thinks like, "they would have never done" this or that. For example, it's possible that the tent is about to collapse and Igor says, "wake up, we must secure the tent immediately, leave everything where it is and grab hold of the canvas where you can." They then position the canvas as he requests and puts some snow on top, then one flashlight goes on top of that, and then he tells them they will go to the treeline and start a campfire, returning at sunrise.