Maybe cause the Senator isn't a real friend, more a 'business-partner', while Vito considered Luca Brasi as a friend. They had know each other since the 'good days', and Luca wiped out single-handedly the Irish group that shot Vito.
Is there btw something in the book of when Luca and Vito met? Probably, but I'm too lazy too look it up. It has to be after 1927, cause Luca wasn't in GFII.
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See, we can act as smart as we want, but at the end of the day, we still follow a guy who fucks himself with kebab skewers.
