I’ll take Occam’s Razor over that tortured rationale you’ve invented for why Adam’s wrote what he did.
Adams tells us in his essay why he chose to examine the legal issues of secession so long after the war that he had fought in. Because no one else had bothered to examine it, and he was both an historian and a scholar.
He never once mentions race, but your explanation is based upon the idea that race is what motivated him. That reads like the Left’s most popular explanation for everything that they disapprove of, attribute it to hidden racism. Don’t know why you’d want to go there.
Well at least this time the target of a racism accusation is the scion of the most prominent New England family in American political history instead of the usual Southern whipping boy, so you deserve credit for breaking new ground.
The Adamses felt that the country was slipping away from them and from people like themselves. That explains a lot of CFA Jr.'s life and writing. Same thing for his brother Henry.
Read CFA Jr.'s 1913 Founders' Day Address at the University of South Carolina.
In this all-important respect I do not hesitate to say we theorists and abstractionists of the North, throughout that long anti-slavery discussion which ended with the 1861 clash of arms, were thoroughly wrong. In utter disregard of fundamental, scientific facts, we theoretically believed that all men — no matter what might be the color of their skin, or the texture of their hair — were, if placed under exactly similar conditions, in essentials the same. In other words, we indulged in the curious and, as is now admitted, utterly erroneous theory that the African was, so to speak, an Anglo-Saxon, or, if you will, a Yankee " who had never had a chance," — a fellow-man who was guilty, as we chose to express it, of a skin not colored like our own. In other words, though carved in ebony, he also was in the image of God.
Adams still believed slavery was technically wrong, but his conviction that Whites and Blacks were not equal did much to explain his increasing softness towards the Confederacy.
As I said before, he doesn't go deeply into the historical and legal background, so it's not out of place to attribute his conversion and his very emotional essay to his views on race.