"So Capone owed his fealty — and he basically always operated — within the realm of the Napolitani/Calabrese underworld."

What I meant by inconsistancy was that Masseria would be inconsistant in rejecting keeping Capone out while admitting Costello,Genovese,Valachi,Bender,Doto ,etc
So it wasn't so much that Capone was Neapolitan,as much as he was farther away and was a Camorrrista and that's where Masseria previously saw Capone's loyaly to be before offering him membership if he got rid of Aiello.