The article on the brouhaha at The Atlantic summarized the broader complaint made by Ta-Nehisi Coates that included the publication's history on race science -- Andrew Sullivan's editorship, the Bell Curve, etc.

Sullivan and the Bell Curve both essentialize "race" as an indelible and meaningful physiological (neurological, psychological, biological) difference between humans. Whether for Douglass in the 19th century or for Coates and other Black Americans in the 21st century, to even ask the question if there is some meaningful correlation between race and IQ is to presume an essential, meaningful, and indelible difference between "races," and therefore to shatter the fundamental unity of the human family.

The most charitable defense for taking seriously The Bell Curve or Andrew Sullivan's writing on race and IQ has been (and remains) ideological diversity or viewpoint diversity. That's what Coates was specifically referring to. But for Douglass or for Coates, a question that takes race as an essential, meaningful physiological category, is axiomatically out of bounds, an unserious intellectual question and a vicious social question. It's a question that comes either from a position of such faulty premises that it cannot be taken seriously or from such profound and disqualifying racism that it should not be taken seriously.

That's my understanding of what both Douglass and Coates were/are getting at. And I think they were/are both correct and right.