i'm not sure that this is damaging to the dems. after all, they can note that HE made this a stipulation and they wouldn't speak with him. they also can deny that they spoke of the documents. this can be spun into a positive for them.
Nobody will believe anything any of these people say. They have no credibility.
The blood's in the water. I expect some investigative reporters want to be the next Woodward and Bernstein, and are digging, as we speak.