they were very lucky. Or I should say - he was.
I agree that it is tragic that the young lady missed 'rescue' by 3 days.

I would have guessed bad weather as the likely cause - and sure enough ...

not sure there are easy answers to this type of situation. especially if you are off-route, compared to where most people trek. it sounds like they must have been exploring a path that was rarely traveled. The terrain looks bleak, not much to survive on. I would imagine that "keeping a positive mental attitude" would be an enormous challenge under those conditions. but if your mind fails ... everything will fail.

Pete