If it works, it's a very good idea. A diver would HAVE to surface, where the rapscallion is easily dispatched.
Especially if he is suffering from the bends due to rapid decompression:).
I'm not sure that's true. I've thrown up at 110 feet without any real consequence. And, BTW, I wasn't throwing up into my mask because it covered only my nose and eyes, not my mouth. I even felt better afterward, and, gross as it was, the fish around me didn't miss the opportunity for a meal either.