There's actually a different, very valuable lesson in this one and it really doesn't have anything to do with the details/causes of the accident. It lies within the phrase "near drowning."
I may not get all the physiology exactly correct but the layman's version is that when we have some who almost drowns, even after they're pulled out of the water and seem fine, there can still be fluids slowly accumulating in the lungs. In effect, they are "still" drowning and can succumb to this some time later if no one's looking for this (because everyone thought they were fine).
This is why, quite often in the case of near-drowning, the victim will be hopsitalized overnight for observation. If there's any evidence of fluid accumulation, it can be dealt with. If there's no evidence of it, then they're relased.
It sounds like this guy was pretty bad off. But the walkaway from this is that you can "drown" long after you've been pulled from the water so don't automatically assume everyhting's done with when the victim goes, "Thanks, I'm OK now."
- Ken