Since I last commented here, some of this stuff has hit close to home... My long time (35 years+, perhaps 1500 dives together) buddy has discovered that he's a FOB. (Fat Old Bastard). He was on a trip recently where he suffered an IPE which resolved successfully. However, this lead to trips to his Doctor of course, and then a Cardiologist. After some preliminary tests, the Cardiologist believes he has a serious cardiac blockage. He is slated for further tests and speculation is that an angioplasty (minimum) or bypass surgery will be required.
Why I raise this is that all of this came as a big surprise to him, although not to me. Bear in mind he is obese, hasn't exercised really at all for as long as I have known him, and has a horrible bachelor's diet (one large restaurant meal a day). His fitness level has been a concern of mine for years and I wasn't sure how to deal with it. On the upside, he's an excellent diver, and he isn't afraid to call a dive if he thinks conditions aren't favourable. He is taking this seriously though and has bailed (at some expense) on two planned trips. As much as I hate to see him unable to dive, I am hopeful that this will be the impetus to start to look after himself. Although it will be a long haul.
My point in raising this is only that in his mind, he was perfectly suited to dive. He felt his skill level and experience would make up for any lack of fitness. This guy routinely participates in "big dives"... 220' - 260' trimix. On the dive where he experience the IPE, he completed 18 minutes of deco (on O2) with his lungs effectively filled with fluid.
I suspect that he is not atypical of many of "us"... we were fit at one time, and we remain moderately fit to this day, but a "fit" 50 year old is not the same as a "fit" 30-year old for the vast majority. Up until age 45 or so, I was running on average, 40 - 50 miles a week on rugged, hilly terrain. Fifteen years later, I still consider myself "fit" but I base that on successful completion of an hour on an elliptical trainer and a little light weight training. I have a decent gym in my house and I use it. Most of us are in a certain amount of denial about our true fitness level.
Back to the original topic of this thread, I agree completely with what the OP is considering, but short of insisting that prospective guests have a legitimate diving physical including a stress test, I don't know what good this will do, other than damage his business by redirecting a large demographic elsewhere.