First, I was making a reference specifically to your statement defining pointlessness.
Second, as the parent of two gymnasts, what he’s doing and what that gymnast are doing are two different things. Furthermore, 80% of the things gymnasts do are pointless for the average person. They’re displays of strength and flexibility for sport, not functional. Outside of gymnastics they’d never do it again.
If he’s training to compete in an event that requires him to do upside down shoulder shrugs, it isn’t pointless. But based on his physique, I don’t think he does for any other reason than to draw attention to himself. Not because this exercise targets any muscles better than a less dangerous exercise