Oh come on. Do you honestly think this wasn't intentional?
Winegardner realizes the connection b/w the Kennedys and Sinatra and he did a pretty good job novelizing it, just as Puzo started the From Here To Eternity connection in the original novel.
He did this intentionally to probably throw off the people who criticize the novels for lampooning the life of Sinatra, and to reemphasize the weird parallel universe/reality that the Godfather universe exists in.
