Within that context, it seems clear that Vito wasn't just sparing Tom's feelings when he told Tom that Sonny had been a bad don. It also seems likely that at some point in Michael's years of training Vito told him that no one could talk to Sonny, and that his death was on him.
I hadn't thought of that before, Pete, but I think you're right.
Ntra la porta tua lu sangu � sparsu, E nun me mporta si ce muoru accisu... E s'iddu muoru e vaju mparadisu Si nun ce truovo a ttia, mancu ce trasu.
