I would say private replys only have a chance of being intercepted by the feds if they really archive every packet that hits level 3 peers in this country. The NSA uses a technology names Nora which scrubs all traffic passing through it (at different points in the country). Now this doesn’t mean they could decypher exactly what’s in this traffic, but if they want to investigate a particular person they look for their last associated IP addresses and then pull their traffic based upon that.
I would say if this site and it’s database is hosted independantly and only Jim or his staff have access to it you’re pretty safe unless he gets hacked.
NSA is already believed to be archiving virtually all e-mail traffic in the USA, and one should reasonably expect that all political websites get continuous monitoring as well.
It might be a tedious job to search the 4 degrees of connections that link your communications with another person but it is technically quite straight forward to do such a thing for an organization with a good search engine and lots of disk storage farms.
The only other thing needed is a bunch of junior level staffers to pore over the search results until they find what was requested.
Of course, the trace request for you might be number 17,534 in the list and the staff may not get around to it for a while.
Plan accordingly.