This seems like a rather racist assumption. The race of an academic isn’t the sole determinant of his research output.
I don’t know how much research you did into Gutman, but he spent the latter part of his life teaching at historically black colleges.
One of his seminal works was a critique of the way academics paved over some of the social destruction of slavery. Sure, a number of academics “whitewashed” slavery during that time period, but individuals aren’t defined by their time period, or their race. From the brief research I did, I reached a conclusion exactly opposite of the conclusion you reached on him, and I think you’ve done a disservice to his legacy.