I have been in the farrier industry for over three decades. From being close to some of the originators of the more natural style shoeing and barefoot trimming movements from the beginning, and watching this evolve over the last 20 years, I can say with assurance that Dr Butler has strong personal issues against the barefoot movement.
His own text books upon which he has made his name and living ,and his long standing philosophies about hoof function and balance are directly challenged by the newer science.
I was originally trained by his texts and methods, and after 14 years of using them, found that they are no longer valid and need to evolve.
Dr Butler seems to be flat refusing to accept that some of his ideas about hoof balance and function need to change.