The igiss argument is a weak one, if Igiss wanted to say only people with a Z in their name could fly a BS he could, but we are not discussing how silly Igiss could be, we are discussing what makes sense.
This whole ID scheme makes no RP sense. It's simply a way for a faction leader to consolodate power into the hands of the factions by nerfing non faction ID's and putting all cap ships above GB (and in some cases GB's) in faction control.