I agree with Eurocentric that it is most likely a call of nature. I think the thin arms are a result of how photography works with focus of the lense .
From help at our friend Google we can observe similar outcomes of the human figure.in photos out of focus.
However, the sequence of these photos has always raised a question in my mind. If there were outsiders or internal fights, is this the start?
The reason being from the details in the photo. It looks like Thibeaux was on his skis then pushed. Joking aside, this could have lead to unnecessary injury, for example twisting an ankle when the foot is still in the bindings, landing on some sharp stick or wood under the snow. Why take the risk of injuring a friend in such a remote place?. Whatever Thibeaux was doing, he had his gloves off. Most likely a prank or joke as whoever the photographer was, the were ready to take a sequence of pictures. But there is no smile on Thibeaux face.
I also wonder if this is related to the snowman phrase.? It was a joke and Thibeaux was the snowman?.
I posed the same question about Nicolas’s expression in another post, because it looks like he’s clowning around, but his expression seems to get more serious and worried with each photo, until the last of the three looks like he’s either pleading or asking for help. The only reason anyone offered was that he was afraid the photographer was going to take a picture of him answering a call of nature. Also, Nicolai was something of a jokester and was not above rolling around on the ground as a couple of earlier photos show. He is somewhat smiling in the first photo. So maybe he fell down of his own volition and found he was having a hard time getting up without assistance? The photographer is literary standing over him to take the last picture, which appears somewhat sinister. However, maybe the person moved forward to help him, but took a picture real fast, so everyone could have a good laugh later at Nicolas’s expense. “Yeah, guys. Nicolai’s antics led to him falling in a hole. I had to help him out!”
In any case, the figure is not a Yeti. In addition to the evidence from other posters that refutes this claim, I would add that if you look at th figure carefully, you can see a hard line at his waist caused by a change in tone between his top and bottom half. I don’t really think a creature’s fur would change either color or tone so abruptly like that. It looks more like the figure is wearing a jacket and pants that are different colors or different tones.
As for the mysterious figure, it could be an enactment for the Evening Ortorten. I remember reading that someone who actually saw the original pamphlet believed that it was in Semyon’s writing and that it contained pictures that Semyon had drawn, for which he praised his artistic ability. So Yuri Kri does his best Yeti impression for “proof” of the highly esteemed newspaper’s claim that Snowmen exist, which may have included bulking himself up by adding layers of clothing. And while Semyon quickly sketched the scene for the pamphlet, Nicolai, being the goofball that he was snapped a picture of it.
However, if it was someone up to no good, that would mean a would-be assassin was so incompetent he didn’t realize he was being photographed, even though he was looking in the general direction of the photographer, line of sight dictating that if they can see you, you can see them. Or he did know, but didn’t feel the need to get his hands on the camera and destroy that evidence of his culpability. That doesn’t make any sense to me. A more likely scenario is that after he completed his gruesome act, he ransacked the whole tent, gathering up every camera or film that was in it and left with them. Of course, that didn’t happen, because we’re looking at the picture right now.