Basically I used to believe that it was very cold, around -30, that night and because they had a single layer canvas tent, stove was not used, they had no sleeping bags, and no possibility of a campfire near the tent, trying to spend the night on the slope in itself would have been deadly. This is why I was interested in conditions needed to form the "raised footprints", as some have suggested that it needs "warm" / near 0C temperatures so the snow is a bit wet. Well, some sources on the internet suggest otherwise, although it looks like raised footprints form in some of the dryest as well as wettest cold places on earth, from Antarctica to Scotland...
However, given the current weather near the pass, which is "warm", it looks like my original assumption might be wrong and maybe spending a night without a stove was not in itself that dangerous.