If you are not a media photographer, then a cosplayer has a right to refuse to be photographed. If you keep stalking and photographing this particular cosplayer, then you will know what will happen. Better leave this cosplayer alone. I had come across a several cosplayers who refused to be photographed, and I respected them. I moved on and shoot other cosplayers.
Putting all the other behavior aside and just looking at the photography issue, if the photographer is just being an aggressive jerk in general to people of either gender, then I'd say it's just your garden-variety harassment. I agree that this kind of behavior shouldn't be lumped in together with
sexual harassment. If a photographer is doing this
only to women and trying to get shots under clothing, then that should be considered sexual harassment. I suppose it could be difficult, however, to enforce the rules and figure out when it's the former case or the latter.