Sure, it's not "pure" black, but his argument is more that the average monitor's #000 text on a #fff background still has too much contrast for comfortable reading.
But I didn't get much out of the article discussing the idea of black on white for text. The majority of his post was about the color of elements on the page. I'm not saying I disagree with his point, but the talk about pure black when it doesn't exist in that context makes it seem strangely written. Looking at it in terms of contrast then it makes with the thought of grays versus black.