I wasn't much of a competitive swimmer, but I was on the swim team and swam my share of laps, both as a kid, in high school, throughout college, and 25 years later this summer at the gym.
They said the water was 84 degrees F. I don't know about you, but if the water is about about 80 deg F, I get overheated while swimming laps. When we used to fire up the water heater in our backyard pool on a rainy day, 84 deg was enough to make it very cozy, and definately steaming, and that was in the deep South!
84 degrees doesn't provide enough cooling for a human body in great shape from overheating. There's no valid coroner finding of "overexertion." It's either "heat exhaustion" or "heat stroke," and if it's either, particular with others who were complaining of swollen limbs, water loss, and confusion, all clear signs of overheating, then the water temp was simply too warm for competition, particularly for a 15k open-water race.
As a former Red Cross Water Safety Instructor, I fully support any measures FINA might make towards setting a maximum allowable temperature for competitive events.
"Swimming officials in the UAE canceled the 15km open water event which was scheduled to be held Wednesday at the same location, with swimmers having expressed concerns."
Good for the UAE officials!!! Bad on FINA.