Since we are cancelling people based on their racism ...

The "settled science" at the time was conclusive according to the "progressive" Charles Darwin.

.... For example, Rutledge Dennis examined Darwin’s role in scientific racism for The Journal of Negro Education and found that in Darwin’s world view, “talent and virtue were features to be identified solely with Europeans” (243). White supremacy is clearly embedded in The Descent of Man, regardless of Darwin’s brilliance or the accuracy of the rest of his theory. ....