TG--
McDonald used the term "contract source" rather than "contract agent."
Big deal.
You (and FL) are shooting in the dark on a foggy night with a pop-gun, and upon not hitting anything, you declare, "There ain't nothing out there."
Shaw worked for the CIA, and was highly paid. Get over it. Shaw was a source of information, but likely not an agent, involved in any type of operations.
So it goes. IMHO, does not change the complexion of the JFKA much.