Good find!
It's worth noting that he exempted Black Southerners from the Sherman covenants- obviously to avoid this being interpreted as a racial covenant- which the Supreme Court held as unconstitutional in the 50's.
Also, not allowing redwood on the land partly because there is one named after Sherman and partly due to "certain environmental views shared and held by the authors." That's an attempt to get around the "touch and concern" requirement. I don't know the law in South Carolina, but in NY courts will usually strike down a negative covenant if it doesn't "touch and concern" the land.
Some clever lawyering, there.