I don't know if it was bullying in this case, but usually it's people just wanting what they've been asked not to take. They think they're being clever if they can sneak you in the shot. Extra points if they can manage to get it online and tag you in it! Never mind you have reasons for not wanting that to happen, reasons you do not owe them to explain.
I do have one friend I need to figure something out with, though. He simply has forgotten my aversion, and after every convention, I wind up tagged in a photo. He's a gentleman in every way, I KNOW he's not doing it on purpose, but I feel so awkward asking him to leave me out of the pictures.