My answer to you is rather simple but may hold some water.
FBI files.
I think it's safe to assume that Janet Reno provided the Clintons, especially Hitlery, detailed info on all the higher eschelons who worked for the Clinton administration.
I always think about these FBI files when pubbies seem so weak on Clinton, but haven't thought about the same going for their so-called friends. You are probably right, subtle blackmail can go in many ways.