The dive shop missed the mark if they did in fact see him symptomatic, and if he had to abort the dive to use an inhaler I have to assume he was, then let him continue without at least some additional investigation of his control and tolerence to diving.
I agree completely with this.
Over my time teaching (about 2500 certs of various levels) I "only" lost one student... and it was an oddball situation.
On the first night of a "Basic" NAUI course, I was caught in a massive snow storm and was not going to be able to get back to the town where the course was being held. I called an Instructor friend and asked if she could cover for me. After the roads reopened, I made it home at about 11 PM. My phone was ringing as I came in. It was my girlfriend (and recent AI graduate). She was very upset and advised that one of the new students had died in the pool! During the "watermanship evaluation" in the pool, staff noticed this guy at the bottom of the pool during the water-tread bit. They dragged him out, began CPR. The fire station was right next door, and EMS was there in about 4 minutes. They carted him away, but he was pronounced on arrival at the hospital.
I never met this man but he was 42, played tennis several times a week and was a regular runner. From what I was told he was of average build and by all accounts, fit and healthy.
There was an inquest of course, and when the Coroner delivered his report on the autopsy, he advised that of this guys cardiac arteries were almost completely blocked. Cause of death was a massive heart attack. He died so fast, he didn't even have time to drown! The coroner went on to say that this man almost certainly would have died shovelling snow the next morning.
At that point, the family's lawyers closed their notebooks and left.
I should add that the gentleman who died was a Doctor.... an orthopaedic specialist I believe.
My point in this is that sometimes people aren't aware of what's wrong with them, or perhaps they are in denial.
I recall attending a seminar at a NAUI conference towards the end of my teaching time, and being told that we needed to be brutally honest about the risks with diving with students right at the beginning of the course. While we had them sign waivers, the NAUI lawyer basically said that in order for a waiver to be legit, the person signing it needs to be aware of the risks and well informed. Prior to this blunt warning we were to deliver, a new student couldn't possible be aware of the risks in diving simply because he wasn't a diver. The only exposure a new student had to diving was likely the fancy posters and brochures at the dive shop and ads in magazines. All sunshine and pretty fish.
As Instructors, we were told that out first class was to begin something like this: "Hi, I'm Stoo and I will be your diving instructor. Thanks for coming. I must tell you something about this awesome sport however... On occasion, people die while they are diving. Usually there's an obvious cause, but not always. Sometimes divers can be doing everything right, and they might still die. It's unlikely, but you might have any one of the following 18 things go wrong..." And then list everything from shark bites to boat strikes to IPEs, embolisms to DCS. Oddly, nobody ever got up and left, but it became pretty common to lose a few by the second night of the course.
Anyway, my point is that a new student is often completely in the dark about diving, and in some cases, their health as well. And some are in denial. It's incumbent on shops and Instructors and Doctors who are doing medicals to do their jobs properly. Failure to do so will result in people getting hurt, or worse. Shops are unfortunately faced with economic factors with trying to fill classes, and are undoubtedly lowering the bar beyond the point of good sense, in favour of trying to make a little money.
How many shops have taken "morbidly obese" people into classes knowing full well that that person is at increased risk for any number of things? Or non-swimmers, or heavy smokers? And how many students are less than honest with their medical histories? I suspect it's a large percentage, especially as the average entry age to the sport has climbed to the point where we must be competing primarily against lawn-bowling leagues for business.