So the IWR attempt was unwise, to say the least. But did it actually make things worse in this case? Or was the problem just their refusal to seek the proper treatment, which continued for hours after they returned to shore anyway?
A couple other thoughts:
-The post describes the kid surfacing after a safety stop, and says that after he got on board things went south quickly, so mom put him back in the water with a diver to sit at 25 feet and "simmer down." So a) she knew there was a problem, and b) she must have known what the problem was. What else could going back to 25 feet possibly be intended to accomplish? It wasn't that she thought he skipped a safety stop and should go back and do it just in case; she said he did one. It's not something you do for jellyfish stings or dehydration or any problem other than DCS. So how did she know, and act on that knowledge, and yet remain in denial?
-Maybe neither of them were certified, or maybe they both were. But at some point, someone who was not working off an OW textbook taught them something about IWR. I doubt she came up with the idea herself that day when she noticed things were quickly going south with her son. Perhaps someone told them that the symptoms we recognize as indicating DCS are just a normal thing that happens after some dives, and can be fixed with a quick and dirty "simmer down." Perhaps this wasn't the first time one of them had been bent, or attempted IWR, just the first time it didn't turn out OK.
-If this sort of thing is a widespread practice in some groups, maybe SSI* has the better approach by explicitly advising against it. I had a first aid manual once that specifically said not to treat burns with butter. It never would have occurred to me to do so, but apparently that's a thing people believe in.
-Seriously, though, what's the deal with this boat? Who was in charge? Did they know about the IWR attempt? Was it perhaps even their idea? Did they not have oxygen on board? Did nobody else notice anything amiss, or say anything to them, or call 911?
*edited; I originally wrote SDI but then double- checked and saw it was SSI that addresses it. SDI might also, or not.