That's how perverse it is. They are firearms on the mainland, just that they are exempt from licensing. It's the fact that they are exempt means they can't qualify for the EFP.
Maybe we should all register with a NI home address but keep the rifles here on the mainland. No, that would not work as the rifles would be on ticket and supposedly we could not use them at FT events.
Which begs the question, if your rifles in NI are on ticket, how come you are allowed to shoot them at mainland events, or aren't you?