In post 26, the author simply states that Stephens asked Lincoln the question. He doesn't make attribution in the quoted text. It's probably in the footnotes of the original article.
In post 22, Hunter is cited as the one who raised the question. It's possible that both Hunter and Stephens pursued this matter with Lincoln. In the quoted text given in that post, attribution for the story is given to both Stephens and Campbell.
I don't think anybody believed then or believes now, that Lincoln was making a "racist attack" on black people -- only that he was not losing any sleep over their plight as freed men. Lincoln had already gone on record with his belief that blacks could not adequately integrate into white society and, as has been noted, he proposed to Douglass and others that blacks be resettled abroad.
While there is variation in the Hampton Roads accounts, the only "radical" difference I see is in the interpretations offered. If you believe Professor Wilson has an "agenda," please state your basis for that belief. If it's the mere fact that he's Southern, then similar claims of bias could be made toward Northern sources.
Wilson is on the Board of Directors for the League of the South. He has a definite agenda.