Shippers had access to members of the intelligence community and Congressmen and Senators who sit on the Intelligence Committees of Congress.
He also had access to many classified documents during the impeachment proceedings and Senate trials. These documents pertained to matters of national security and were much more significant than just Clinton sex escapades.
Schippers writes about this in his book "Sellout" and complains that the Senators did not want much of this classified info brought out against Clinton in charges since they feared it would be harmful to the stability of the country and to the careers of some Republicans and Democrats.