Let's not wet ourselves. The guy wrote his doctoral dissertation on the subject. It was published in 1971. For all we know, and by all evidence, he went on to do other things and never studied the whiskey industry again. He wasn't a distiller, didn't spend time with distillers. He just read a lot of old documents and wrote a paper. Don't get me wrong, it's an important work, and has been very valuable to me personally, but there's no reason to believe he knows one iota more than what is in the book.
I am surprised to hear he's 91, which makes him like 54 when the book was originally published. Either he finished his PhD relatively late in life or there was a big gap between when he did the initial PhD work and when the book came together. Nothing wrong with any of that and it's not uncommon for someone to rework their dissertation into a book years after the dissertation itself was written.
It would be interesting just to learn what prompted him to do that subject and what the reaction to it was, both from his committee and then from the broader audience when the book came out.
Mike can speak to this better than me, because he's in the university libraries down there more than I am, but you would think that lots of history graduate students at Kentucky universities would look at whiskey-related subjects, but very few do.