Yes, you've got the right "historian" I was referring to. The people he fell in with saw the South as a separate nation under occupation, and believe that secession is both desirable and inevitable. To bolster their separate nation thesis, it was necessary to postulate the bizarre theory that Southerners are a different race from Northerners. It's sad, really, because he started off as a gifted historiographer, and ended up effectively marginalized.
There is another example -- still living -- of an historian who made an early name for himself researching and writing about some of the early battles of World War II. Then he apparently found that fame and fortune were available to a talented writer who could rewrite history to pander to black Americans. Under his guidance, the Civil War became a war of extermination of blacks. He writes endlessly about atrocities committed by Confederate forces -- well, you get the drift. It worked for him -- he landed a professorship at a black university, made a movie, and so on. But his credibility, outside his fan club, has suffered.
Thank God we still have real historians who read, study and critically analyze the past for no reason other than a passionate devotion to the truth -- as unattractive as that truth may be sometimes.