The novel provides the missing detail. After the meeting, when the Don back home, meeting with Tom, he (Tom) says that he doesn't believe the Don doesn't want to know how Sonny was set up, or that he has given "your enemies the victory today...you've constructed a magnificent riddle that I can't solve." The novel then says that an "immense look of satisfaction came over the Don's face...well, you know me better than anyone...even though you're not a Sicilian, I made you one. There's an answer and you'll comprehend it..."