The problem you're describing sounds more like a societal/work-culture problem that's completely orthogonal to the study.
Cold showering improved individual health: the fact that those experiencing said improved health made unwise decisions that may increase the spread of disease doesn't change the fact.
Perhaps what we have here is a concrete example of the principle put forward by Mark Twain - “Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day.”
