My understanding of the social context was that his views were extreme even for his era. Eg, I gave two examples of his authors who were less extreme than he was.

The Voting Rights Act of 1965 prohibited racial discrimination in voting. Blacks could and did certainly vote long before then. Blacks, for example, voted immediately after the Civil War. It wasn't until the end of the Reconstruction Era and the repeal of most of the Enforcement Acts that blacks were deliberately disenfranchised by state governments run by racist whites.