I'm not a diver, yet, so you can take my two cents with a grain of salt, but.. I've seen lots of regulations that may make no sense, certain hand movements are signs that mean certain important things, and a lot of pointless 'taboo' things related to safety in my short time I spent in the Air Force (although a lot is just due to tradition). And they don't always make sense, but they have their purpose.. Some of them are pretty stupid, I admit, but that's no excuse not to take certain things seriously, like safety.
That said, I've never seen any sort of 'serious distress' signal that coincides with exactly what many people just do naturally (while not in distress). That concept makes absolutely no sense to me, especially considering there are a large number of much more obvious signs of a diver in distress.
It sounds to me like one of the many things in our society where people love to find something they can get offended about. So many people just enjoy having that power over someone.. "You broke my arbitrary rule and now this and that!"
But I won't be putting my mask on my head, anyway. I get too paranoid about stuff like that falling into the abyss.