I'll dive with obese people. I've got no qualms about that. I've already made my peace with the fact that the buddy system fails far too often. I'll just carry my pony. It's great that they're getting into the water. Can't think of a better way to get active and lose weight than swimming.
Without being there, can't comment on whether or not it was a heart attack or what without the autopsy results.
That BMI calculator only works for normal shaped people. I'm built more like a big ole Viking. I'd be a Clydesdale if was a horse. Completely lean I'd be around 215@6'3, no way in heck I could get down below 200 without losing a ton of muscle mass or being really, really sick.
I'm at a BMI of 31 right now. And I know I need to lose 25-30 pounds before getting more serious about diving. Yeah my legs are strong, so's my back and everything else. But if I trip and get a sore knee because of my weight, then all the strength in the world can't make up for pure knee pain in the water. Knee pain sucks for diving. When it's gone, I can out swim anyone, but when it's there, I'm just on an elevator ride.
Plenty of ways to fix my knees. But step one is to lose 25 -30 pounds. Might not need much work after that. Since I have a ton of muscle, it's very easy to lose weight. Average around 2000 calories per day and hardly any more exercise than my day job, and I melt quickly. Not a big deal, I'm already down 10, but going to bed hungry every night (even though I'm fed and full), isn't much fun.