Not sure. Can only speculate that it may have something to do with the unique characteristics of the terrain. I'm not even sure it is the AF. But if it was, or any other DoD org, and a classified program, I wouldn't trust what any of their spokespeople say.
Yes, does the pattern tell you anything. If I recall, one sheriff described it as moving across a grid where the drones would fly across, then down a ways and back across the way they came, and then repeat. Not sure what that would lend itself to except maybe precision terrain plotting.