As long as the operator of the photographing UAV follows the same photography rules and guidelines as the people running around with cameras on the ground, I don't see a problem. Also, shooting down a UAV is a) illegal (property damage) and b) even more dangerous that the actual UAV operation, since a shot-down UAV will surely come down uncontrollably - the responsibility for that damage will then rest on the shooter.
Just as Burning Man is a test bed for civilian use of drones, it will also be a test bed for civilian anti-drone measures. These don't actually have to involve shooting it down, but people are already thinking about it
