His leg was caught in quicksand and he (and the woman with him) couldn’t get out. Between the time they spent trying to free him, her hiking out for cell service, and the rescuers getting there, his leg was in a freezing cold stream of moving water for 10 hours.
I’m actually surprised he survived. I’ve done the Subway and it is a long hike and at this time of year there wouldn’t be many people around (sounds like they never saw anyone else). Both the physical and mental aspect must have been excruciating.