Similarly, Graham almost certainly already has strong opinions on the basic premises of this essay. Thus, the process of revising and polishing his essay to make it readable and compelling doesn't help him spot any of these obvious critiques. As you quoted, he believes the people advocating "people of color" over other terms have no principles. Thus he can't apply their principles to his own essay and anticipate their criticisms. Based on how he describes "wokeness," he seems to think are generally unprincipled.
Neither he nor his reviewers are equipped to analyze the substance, which is why it can be stylistically strong but substantially weak.