I'm struggling to see the jokey and macho competition described as anything more than camaraderie, certainly not an extreme or uncommon attitude. I don't think it means they are ignoring the radiation, just enjoying (rather than dwelling) on the risk associated with their chosen career.

The story conflates these two different incidents, but really they are unrelated. And if the takeaway you have is that they were blase about the risks, well, that isn't at all how I read it. Indeed, it was clear that it was taken seriously.

Steve just didn't have the same attitude and so quit, that is all :)