I don't take such a fatalistic view of the situation given the same skill:
1) given the same skill, if he was tethered - there may have been a possibility of rescue.
2) given the same skill, if he had given coordinates - there may have been the possibility of rescue.
3) given the same skill, if he could have hung on - there may have been the possibility of rescue.
at the most, he was in the water 83 minutes [likely less] . . . will you positively be dead in 83 minutes or be severely hypothermic but still alive. Are those rules, rules? or variables?
or . . . if you are in the glue, do you give up or do you play for time