I don't see anything wrong with the question, and in fact there is a lot right with it. The answer doesn't have to "name names". Just a raw number of how many of the signatories of that letter received payment other than pensions, directly or indirectly, from the CIA within calendar year 2016.
That letter was a disgrace when it was signed, so it's a fair point of inquiry to know if it was essentially funded by the U.S. government.