So lets say he could know how long the whatever age human could survive in x degrees, ok sure, but his body being covered in bloody wounds would severly reduce this time right, so isn't all his mind talk completely wrong?
And in the first place it's pointless because no matter how long he can survive in the heat his goal should be quickest possible way the fuck out of there. So it's just filler right, author needed something to fill the pages?
Seems the original is a webcomic not a novel? If it was a novel there would be much more reasonable text to fill the space with I'm sure... Though just because it existed doesn't mean they'd use it.