I think Sarno being an acting boss is something that was lost in translation between the feds and the press. The feds obviously knew that Sarno was acting boss of Cicero but I think the press ran with it and exaggerated him into being acting boss of the whole Outfit - this after months and years before and after Sarno's arrest where the press named DiFronzo, Andriacchi, Lombardo, D'Amico, and Marcello as "boss" in some form or fashion. It's not really something that was necessarily disputed either - busting a boss is a big thing and John Q. Public doesn't differentiate between a crew boss and a family boss, all they hear is "boss" and it sounds good to them.