Your theory is interesting. I still think that the whole thing caused some little known physical phenomenon, and I do not see it as a coincidence that orange spheres were observed in that area at that time. The only problem with NO2 theory is that:
1. After leaving the tent, they behaved rationally (organized departure, their traces were clear and there were no contours of the body / hands on the snow only their feet, so it is clear that they went upright and were not injured). After gas intoxication, walking would be altogether different.
2. If NO2 was created in the tent, it was enough to get out and tilt the tent and get to dress. I do not believe that there would be too much NO2 when it happened that it could not be diluted with ambient air. I do not know, but it seems to me that there is something wrong with the tent that they could not touch him, overturn him, perhaps he could be under electric charge? The same can be said of e.g. CO2 from stove, as some say. It was enough to go out and overturn or cut through the tent and pick things up.
Plasmoid can be in the solar win and it is proved that at that time there was a strong eruption from the sun. And this area on the Urals is anomalous due to the composition of the soil and the rocks, and “something” could have been created there, which we cannot imagine now. And, of course, NO2 theory is highly probable. Personally, I do not believe it has caused some bombs or weapons, but it has caused the very nature. Some people speculate that the classical ball lighting has a lifetime of up to 4 seconds. But somewhere I read that some of the balls they assume are plasmoids were seen for 7 hours.
What I absolutely do not understand is why Zolotarev had a camera on his neck and why he did not make any picture. He had enough time, assuming he died a few hours after leaving the tent.
In terms of bruises and minor injuries, they probably arose when the trio tried to return to the tent and were already weak, so they did not go upright but occasionally fell and under the snow were the small rocks.