At the end of the post he did write "From a technical perspective, authentication defines who someone is and authorization defines what they have permission to do. However, I didn't find that terminology useful for my purposes here."
Was that there an hour ago? I'm surprised I missed it.
I have no idea but on at least one occasion someone changed what their article said after I remarked on it on HN. HN is pretty well known. I wouldn't be surprised if they updated it because of your remark, as appears to have happened once in a different article/blog because of a remark I made (thus making me look "dumb" at the time).