That was my first guess too, but the rankings say it was still active till 23:05: http://hnrankings.info/6594352/

... but of course they don't mention what timezone that is, so I have no idea how long ago that was.

Also, the article contains comments whose timestamps differ by more than two hours. That wouldn't be possible if the submitter deleted it.

The post seemed to be on the front page for longer than an hour, from what I remember. Looking at the link. it seems omments were being made (by various users, not just two people going at it in a dead thread) several hours after the posting