I don't see where he has committed any unlawful act. The age of consent in DC is 16, and apparently none of the pages took him up on his offers anyway.
The FBI would have difficulty getting a search warrant, and in any case he's not so dumb that he wouldn't have chucked his hard drive by now.
Why did this kid keep up the correspondence? He must have been having a good laugh.
Anyone with mildly functioning gaydar would suspect that Foley is gay. It sounds like the pages discussed it. This particular page handed Foley at note when he left. I think that's kind of weird unless you go around to every office and hand each congressman a note. Maybe it started as a lark to see if Foley would take the bait. Well, he did, but I don't think that makes him a pedophile. After all, Foley had a pretty good example of the fact that the Congress doesn't take this sort of thing too seriously in the way Gerry Studds was allowed to have sex with a page and then retire in his own good time.