This was a deliberately poor phrasing of the "10 foot wall, 12 foot ladder" adage.
Right, but the comparison isn't perfect here because wall height is linear in the analogy, but searching for exploits in an existing piece of code reaches a point where either there are none left to find, or finding the next exploit would take years. That's the stalemate point I referred to. (Any high-stakes project may end up having its own "red team" agent/s running 24/7 too.)
I know that, as time goes on, it feels like we have less hours in the day, but time is also linear.