Which was implausibly stupid. And what was Zaza saying about having worked very hard to guarantee everybody's profits? Did he provide security for Corleone casino operation? In this case, he kind of had the point and Michael stiffing him was a declaration of war.

Of course, Zaza getting away with the helicopter massacre in a prominent location in 1979 (!) and Michael not being tied to it despite his checks being on all the bodies are huge plot-holes. Particularly since all Atobello and Lucchese had to do to stop Michael's bid for Immobiliare was to embroil him in a public scandal.