Couldn't the person of Foto No. 17 also be Thibeaux-Brignolle?
The photo before (No.16) also shows him in a strange pose.
As well as this photo shows a darkened color and uniform clothing what could be seen as this from the distance.
The only thing that confuses me is the pose in photo 17, but the photos before that were weird poses too. Maybe it's also supposed to make it look like there's a yeti there and they wanted to take a picture like that to tell about it.
I'm more on the theory that it could have been a wild animal, the question is what animals are there right there? And how do they react to the weather conditions that day? And wouldn't that tent with people put her off?
Maybe someone has thoughts and answers on this.