It's the sexual content of the talk that was criminalized, not the act of talking. I'm sure you would know that so I'm confused as to your point. I wish someone who is an expert on the law Foley helped get passed would weigh in on this.
I think the law Foley helped pass was during the last year. That is long past the reported date of all of these messages (both the emails and the IMs). In America, criminal laws cannot be retroactive. Not defending him - simply citing a legal point.