It's not a presentation, ...
it's a book he already has been working 3 years on.
So assuming he wants to get it published when it's finished in another 3 years, he will have the same difficulties as he has now when he wants to bring the finished product to the publisher. It's good he found it out now, so - after correcting this minor issue - he can do the other half the right way immediately.
Thinking you lost 6 years of work must be twice as maddening as thinking you lost 3 years.