To them though there is no such thing as a 'fake' GN drive. Only the Gundam GN drives(green) and the, assumed, rest of Celestial Beings GN drives (red). Since what ever drives where not taken from the rest of CB are assumed to have been on the thrones, it would make sense to assume that the units with red drive at the time served alongside CB and thus would make the Gundams accomplice. Its a perfectly logical train of though, you just have to remember that we, as viewers, are omnipotent in a sense.