He's lurked long enough to know who's who. What a scum. Wish I was young again so... You know.
I'd be wiling to bet that if someone looked hard enough on DU, they'd be able to find out who is doing this. This kind of moron won't be able to keep from bragging about it. There are enough sick "people" on DU that it is the obvious place to look for clues.
I'm not sure which freepers have stomach enough to regularly look at DU, but it might make sense to enlist their help. It is entirely possible that this is not done by a single person. The charge of "conspiracy" can be used for just about anything.