One of your argument is the proportion between the head and the body.
What you forget is the temperature. The guy is overdressed. Its thickness doesn't come from its Menk nature but from layers of jumpers and coats. If you check the size of the tree branch next to him, the distance, etc, it seems pretty impossible he's taller than 6 feet/1m80. Here's what an man dressed for a long time at -40°c looks like with modern, specific materials
check the proportion, you won't find the same than a big guy in t-shirt like the rock !
Your second argument is the face you find in the hanhenced picture.
But this is not the face of the man, it's the edge of his hood. The whites spots come from snow on it, and are made up as a face by enhancement. His actual face is looking to the left (to his right hand actually) and is hidden in the shed of the hood. Otherwise, how do you explain the dark area on the side of the menk's head ? All his right side is far more lighted up than this area, even his armpit is barely shadowed.