Wiki has an interesting entry on the writer, Michael A. Hoffman, who, as you say, they describe as a Holocaust denier and conspiracy theorist.  The latter evidently refers to this:

Another of Hoffman's subjects of study is indentured servitude and slavery in America; he contends that a widespread history of white slavery has been overlooked by most historians. In his book They Were White and They Were Slaves, Hoffman attempts to demonstrate a social structure situating poor whites as holding the lowest post in colonial and post-colonial America

Maybe we can eventually make language a complete impediment to understanding. -Hobbes