I don't remember if Brando showed anything in his acting that suggests that he was taken aback by Zaluchi's speech. I did note that Tattaglia almost had a smirk on his face following Zaluchi's face though.
Zaluchi was honest. Maybe he really thought his suggestion would help smoothen the situation between the NY Dons.
Vito knew that he had no chance but to agree on the drug proposal. The only question was under which conditions. And his main goal was to bring Michael home safely.
