I would take him at his word and say something like, “No problem. By when do you think you will have finished the book?”
Depending on how they respond, schedule the appointment or continue to explore giving them time to read the book and work toward scheduling the phone appointment for some time in the future after they have read the book.
Depending on how the discussion is going, I might ask something like, “Do you really want to read the whole book before you talk to me or are you just looking for a polite way to get rid of me? (With a sincere interest to know the truth and a Trusted Advisor Way of Being versus a sarcastic salesperson trying to be in their face.)
If they sincerely want to read the book and then talk to you they will work with you to determine a time-frame and set a phone appointment to have the discussion about how the book will have a positive impact on something that’s Meaningful, Important, Significant, & Compelling to them.
If they are just looking to get rid of you then you will have a difficult time getting a commitment from them.
If it’s a put-off, it probably stems from their belief that you are not genuinely trying to add value and be of service, but that you are really just trying to sell them something. What about you? Are you truly calling to be of service or are you selling? Listen to your recordings.
At the end of the day, remember your goal is to add Ideal Clients at the rate that will get you done, not get into an objection handling battle where you try to convince everyone that you get referred to be your client. Don’t get stuck and frustrated with the people who don’t get it.