"And the Air Force has much interest in dead, ancient civilizations? Here I thought they only cared about drones and terrorists."

There is definitely more to this story than what Daniel is telling him; then again, there's a lot more to his story than what Lucifer mentioned, so it's really all equivalent. And it's not as though Lucifer has much leverage to force Daniel to divulge it, nor does he want to waste his energy going brain-spelunking in order to find out. Before, it may have been something that he would have been curious about, but he doesn't have the luxury of indulging it now.

"Do you have a specialty? One particular culture or period?"