[douglas]

One of the standard black hole abilities, either destructive center or movement towards center, triggers a special AI pathing routine that tries to stick to the edge of the system rather than just avoiding the one sector that actually does damage, even to the extent of wasting movement points sometimes. That routine will usually keep the AI out of the dangerous area of your custom black hole even without the damaging storms, except maybe for the corners, and even for the corners it will almost certainly get the AI's ships close enough to the edge that the standard damaging-storm-avoidance routine will work.