The evil and hated Southerners wanted his ancestors to count the same as a freeman because that would have tipped the House of Representatives far in the South's favor in terms of representation. The godly and sainted Northerners didn't want to count slaves because then the North could maintain some say in how revenue bills and tariffs were passed, among other things.
There was certainly no moral superiority in the Southern stance, if that's what you were implying.
Oh NOES!!! Can't have that!!!
As I said, "Three Fifths" was a compromise. Many people take it out of context, including this author.
And that, my FRiends, is all I have to say about that.