Still Another Day in the Life - S7-E22
Ben Veloric: I guess I just wanted to find out of she loved me for myself.
Harry Stone: Now I guess you know, all she cares about is money.
Ben Veloric: Yeah. So, Debbie, are we back on?
Debbie Rollins: You mean you don't care that I'm shallow and materialistic?
Ben Veloric: Heck no, as long as you don't chunk up.
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.