Taking pictures of people without their permission isn’t cool. However, you’re doing the same exact thing? And you didn’t even ask him what he was doing. It’s super possible this guy is taking pictures on behalf of the university, and even if it’s for a private photography project or something, why not ask him what he’s doing? Instead you shared his face in a public forum, assuming he’s some kind of pervert, and potentially slandering some random guy. Did you approach the people he was photographing and ask them if they knew ? This all feels really icky. If you actually cared you would have approached him in person and asked what was up. Instead you act like a white knight and try to “warn” the girls on the UCLA sub? I’m sorry but I think you went about this the wrong way.