Essentially he wants people to be able to use it as a workbook, and not as a quick read (if that's even possible).
That said, I'm fairly frustrated that there is no electronic version. I like to take book notes too, but I like to take them on my Kindle, and I have no plans to buy more paper books. I feel like both the author and I are missing out because of his uncompromising position. (Assuming his position is what the Quora post claims..)
I don't think that revenue would be as significant to him as it would be to the average person.
So it seems more of a control thing, which I find unfortunate. Maybe the paper version is 'better', but presumably, if the book is good, an eBook version would be better than no version, and for some people, that is the choice.