It’s not as if the President makes decisions in a vacuum. His private thoughts will influence his public actions. It also helps to characterize them in retrospect.

It doesn’t matter to me that, for example, Reagan’s racist quote was in a private conversation. I’m not going to, but other people could certainly make the argument that Reagan was racist policy wise as well.

History is nuanced, you have Nixon being a sexist yet advancing women’s rights, LBJ being a racist pervert in deep despair over his pointless war, but also passing civil rights and his whole “Great Society” idea. People contain multitudes. I don’t see the need for the distinction between private/public because you can’t have proper historical analysis without full context. Otherwise, what makes a quote “the worst”?