No, it’s not clever, because it’s wrong. Absence of evidence can exist in any situation, whether the contested thing happened or not.
That’s logic.
The statement is not clever, that was the CIA guy’s point, and it’s not even circular in the logical meaning. It just has the word “evidence” in it twice. That doesn’t make it circular.
It’s circular in that whatever is deemed proof becomes evidence. I think the CIA guy was doing trying to do the thing Donald Rumsfeld put forward about known and unknow.