Okay, 115 is darn hot and if you've ever ridden a motorcycle in temps like that, it's hideous (especially on an air-cooled 2-stroke).
The fellow who died was 69 years old and still leading young men on adventures. 69 years old. He was apparently in good health, in compliance with the BSA requirement for annual health assessment and got caught in temperatures and stress that exceeded his capacity. I wonder if, once things got that hot, he had a chance to cool or not. That was pretty darn hot and those Scouts had to deal with a pretty horrible situation.
BTW, BSA standards direct us to cancel all kinds of things during "weather", be it rain, sleet, snow, heat or wind. Such guidelines can be difficult to navigate once one is "out in it". For examples, one is hiking in the High Sierra and it begins to rain; one is canoeing down the Colorado and wind whips up; one is canyoneering and it becomes much hotter than the weather forecasts that were available for the nearby areas. The spreadsheet and flow charts begin.
They got caught out and a good man, a volunteer, lost his life. A disaster all around. My heart goes out to those young men and the Scout leader's family.