The way I interpret such a gesture is that, whatever agency that approached
him, made him promise (/swear, or whatever) first that he wouldn't "tell"
anyone else about such conversation.
(I know of other people who are a nuisance to the establishment, that were
approached by it, in an attempt to be "recruited" to its side, with a promise
first that such a conversation would be "off the record".)
And, I've seen this kind of response before...
Once, when a well-known journalist was asking "sensitive" questions to a
military guy, that was denouncing other stuff and that, obviously, couldn't
answer the more sensitive ones, and the military guy would just start
singing, in very short and high pitch bursts, in response to them, in what
appeared to be confirmations to some of the questions asked.
