I thought that, too, at first glance. But on re-reading, that sentence seems to explain the reason for the following sentences, which were statements of atonement for any of SB's past support for slavery or Jim Crow. Without the explanation, it might not have been so clear as to why this issue was raised. They were putting it in the historic past, not commenting on some recent embarrassment.
you will never, ever see an article with the words...the kkk founded by dimocrats....