I have seen AI fire missiles from the D6D and the MDC as well. The only noticable difference though is that they have fired usually from a range of 2 or less, and never from a distance. This has happened with ai vs ai and ai vs me in missions. If the ships do not go close range, they dont seem to fire their drones. Next time or 5 you see ai with drones vs you, try not firing and flying really close at slow speeds to see if they do.