What Lilo said.

Plus: the novel has Hagen thinking over what Vito meant by "balls": Was Woltz willing to risk everything on a point of honor? No. "Honor" didn't figure into his equation. He was a businessman, interested in profits, in an industry in which "honor" was practically unknown. He acknowledged to Hagen that Vito could cause major labor problems. How could he make that movie with his own selected leading man if the studio was shut down by labor problems. He figured out that one or more people in his employ, whom he might have trusted, were complicit in Khartoum's killing. And, he probably knew that, when the chips were down, Hoover was too smart--too image-conscious--to allow FBI agents to act as a private army for a "friend."