They owned slaves, too. What's your point?
His source is most likely an article that appeared in a half-size Wiccan underground "zine" called the Green Egg back in 1975. The supposed book he claimed was a great read appears to be an invention of that same article.
There was no such person as “Dr. Burke.” The Smithsonian Institution knew nothing of the so-called American Historical Reference Society. And the hoax was eventually traced to an underground New Left newspaper, the Chicago Seed, which had copied the fabrication from another underground paper, which had apparently made it up.