The person being protected here is Lincoln. Nobody in the Scholarly community wants to say anything bad about Lincoln, and if any Taney biographer mentioned it, they would be castigated by everyone in their social peer group.
Of course they aren't going to mention it. It is a smoking gun that Lincoln was a tyrant.
None of the biographers I've read - James F. Simon, Bernard Steiner, and Walker Lewis - wrote a biography on Lincoln as well. So what motivation would they have to protect him at the expense of not accurately detailing the life of the central figure in their own books?
Nobody in the Scholarly community wants to say anything bad about Lincoln, and if any Taney biographer mentioned it, they would be castigated by everyone in their social peer group.
Do you honest not realize just how stupid that sounds? What's next? Lincoln really was gay but it's being suppressed because any biographer mentioning it would be raked over the coals? Lincoln really was Jewish but any biographer mentioning it would be tarred and feathered and drummed out of the Official Biographers Guild?
What you are suggesting is completely irrational. Oh wait...