I would add a few observations gunmat.
The autopsy is only as good as the individuals and knowledge at the time. They speculate about what may have caused the fracture, in the absence of any weapon or penetration, all they can suggest is a rock.
Having done a bit of research, it would seem hemorrhages happen at areas with synovial membrane during hypothermia and / or freezing. There is synovial membrane where the jaw connects to the temporal skull . Swelling is known to happen with the knees due to some process .
"The findings of synovial membrane hemorrhages and bloody discoloration of synovial fluid of the knee joints are another vital sign of hypothermia."
The autopsy conclusion says;
I believe that SLOBODINA’s death was caused by low temperature /freezing/ as evidenced by: swelling of the meninges, congestion of the internal organs, Vishnevsky spots on the gastric mucosa, frostbite fingers of the upper extremities of the third, fourth degree.It goes on to say.
The indicated closed skull injury was caused by a blunt instrument. At the moment of its occurrence, it undoubtedly caused a state of short-term stunning for SLOBODINA and contributed to the rapid freezing of SLOBODINA. The absence of obvious hemorrhage under the meninges gives reason to believe that SLOBODINA's death occurred precisely as a result of his freezing.From what I understand, the autopsy says Slobodina died from freezing and not what caused the crack. There is no hemorrhage under the meninges, what I think is being said is that freezing was already taking place , it was not the blow to the head by another person ( if there was one?) , It is most likely he fell in a poor exhausted state several times to where he eventually collapsed. At least ,this is what I think they are concluding.
Moving forward a few decades, we have more data regarding hypothermia. We know more than people back in 1959, we do know that on occasion, people have been found with a fracture in their skull or various changes in the neck depending on variables of clothing etc. There is no obvious evidence of outsiders yet , to say it was a blow to the head by outsiders or someone else is equally speculative .
Here's a link that might be of interest. It has some data on hypothermia and various findings.
https://serval.unil.ch/resource/serval:BIB_B1EBC2CBE49E.P001/REF.pdf