Feel free to read his books. He published the data. Do you think all the newspapers which said the same thing at the time were making it up too? Even the Northern newspapers which said the same? How about all the various commentators North, South and Foreign who said the same thing at the time? Were they all just making it up?
Then show us the data. Show us how the South paid 75% of taxes. Show your data.
He does not want to see the truth. He wants to believe the comforting lie we were all taught which justifies the war as a moral crusade. Nobody wants to see their heroes tarnished or revealed to be villains.
I had a bit of a problem with it myself when I first realized the direction the actual data was leading me, but I have never been able to lie to myself, so when I saw it was irrefutable, I just admitted to myself what really happened with the Civil War.
The "good guys" were not the good guys. They were actually the bad guys.