He has been using HN over 900 days, and this is on the front page -- it's quite possible he simply saw the article and comments just like you and I did.
I did see this article, I just didn't read the comments. No idea that this would be here had it not been for that tweet.
So, I just found it not so much an "Aha! Busted!" moment, as much as it was noteworthy.