This seems like an easy call to me. Your job, and your success in your job, is measured by how well you work with others and how well you help advance the mission of the agency. You achieve both goals by cooperating with this political and sharing the information you have. In any event, it isn't a state secret. Plus, one day you may want this political on your precious list of interagency contacts.
If you look at it solely from what is best for your career- you freely share the information. If you look at it solely from what is best for the agency- you freely share the information. It isn't the list of contacts that is important, it is the relationship you have developed with them. You won't lose that just by sharing names.