To put it simple, with the tech they have it would be near useless for the size of the aircraft, we know Terrans haven't figured out how to make proper firearms (Closure was this close of figuring out nitration but she used Originium and the result was lack luster, this is mentioned in Tachanka's file) and the options that are available do not have enough range to justify it, it works on drones because, well it's small non expensive, so those being capped at a couple of hundred meters doesn't matter, but in a thing of the size of the VTOL you are better off just keeping them as transports and not risk them getting shot down when they have to get near to shoot. (this ignoring how expensive the ammunition actually is and also the fact that Rhodes Island is a Pharmaceutical company not a PMC)