Trivia: When Eddie is unsure of the year, Harry says, "it's 1985. Reagan is President." Eddie replies, "the actor?" This is the same response Doc Brown gave Marty McFly in "Back to the Future" when he asks Marty who the President in 1985 was. This episode aired less than 5 months after "Back to the Future" was released.
Trivia: In this episode, the rock star Eddie Devon is played by Michael Ross. Ross was the real-life husband of Markie Post, who plays Christine Sullivan.
Answer: It's possible when Harry called the military, he implied that the book contained sensitive information, seeing as how many government and military officials were part of the client list.
I thought it was because he developed feelings for the madam and couldn't bring himself to turn her in.