This could go on forever. Just because, 10 years or so later, a particular reference refuses to comment on old work does not mean much to me. Many of my friends are the same. They refuse to comment here or to me when I ask them things that are vague in my memory. So, your entire premise to me is faulty.
In addition, I have verification that these conversations did take place. Grant Haist confirmed not only the nature of the conversations but the content and time period. So, I have to say that you are not being fair in this situation.
In addition, if two authors are involved, the senior author is responsible for the veracity (or for verifying) the data as well as the other author. So, this whole thing appears to be an unfair attack to me. I have used the book and found it was a worthwhile investment.
There is absolutely no evidence that the quote in question is inaccurate, merely that the person quoted is no longer interested in responding.