K-Lapse drank too much booze, ate the wrong stuff, etc. So when it gets hot, people like that can't take it.
Eat light with good protein, avoid sugar-high carbs, drink water, and you can take the heat.
I agree good health habits is a key to contributing to a reasonably healthy life.
However, it doesn’t guarantee one.
I agree that people with the lifestyle you have described may have more of a problem with the heat and may be more prone to heat related injuries and illness.
Their chosen lifestyle is really between them and their employer. Unless it puts you in harms way.
I don’t agree that this is proof that a person is faking it.
Accusing someone of faking an illness of any kind is a serious accusation.