That restriction started to ease up years later. But initially --- almost to a Family --- Sicilians headed ALL borgatas with the exception of Chicago under Capone, and one or two other examples in other cities.
Which might be why a possibly significant number of capable non Sicilians possibly declined to join
Thats quite possible, even probable.
And conversely, there were those non-Sicilians who longed for membership, but weren't deemed acceptable, or certain circumstances just didn't allow for it.
So, on review, I think the sword cut both ways.
