If AA was adjusted in that way, which is an interesting idea, it's cost would have to increase to account for the additional function. Not sure by how much, probably *1.1 (IE, +10%) as it affects so few target models. In other words, the AA ability would change from having a cost of *1.5 to a cost *1.6. As this would only adjust the cost of the weaponry and not the whole model, the increase to cost should be minimal.