I thought that was kind of a brilliant comment by the CIA guy. I love when people burst cliches to smithereens anyway, but it was so logically perfect as well.
It’s like everything becomes “evidence,” so what can we say is actual proof? Everything is conditional. But it is a playful, circular and clever bit of reasoning: “absence of evidence is actually evidence of absence.” If you take it to its logical end you end up with skepticism or maybe cynicism.