"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.
Capone had become such a force of nature, that at some point, it behooved Joe Masseria to approach Capone and "woo" him -- for lack of a better word. Aiello and his Mafia Family, based in the City of Chicago, were staunch supporters of the "Castellammarese" who were largely viewed among may Sicilian mafiosi as ballsy "heroes" for bucking and "going to the mattresses" against Masseria, who they viewed as greedy and a tyrant, understand?
Aiello had been sending money and men to augment Maranzano and his troops in their fight against Masseria and his forces. Subsequently, he had become a major thorn in Masseria's side that needed to be removed.
Al Capone turned out to be Masseria's solution to the problem. In one fell swoop, Masseria eliminated his enemy and was able to secure the Chicago territory for the Castellammarese faction.
