Interesting point! But I think Michael was just trying to get Carlo to cut the BS and make his confession, as if to say, "It's all over now." I doubt Michael was thinking about Sonny then.

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.