I am confused!
1. If Fabrizzio was sponsored by the Barzini Family, how "He's in this country illegally...”?
2. what debt?! Michael was still alive

My take, makes no sense to me as to why Barzini's family would bother with Fabrizzio “apparently paid off a debt” when Barzini is dead [if the Baptism murders were in 1955] and the family is in disarray, pretty much exterminated! just ask Paulie....

Besides “1956 sounded way too late” indeed

Don Tommasino's a hundred button men on the street twenty-four hours a day and that Fabrizzio never showed one hair on his ass! and managed "to hide out in Sicily" until his escape to America and running a pizzeria in Buffalo
How's the pizza in this Pizzeria?!

If so, Don Tommasino, Michael and their men were asleep at the wheel!