Is that why it just disappeared from the front page listing?

I can understand tweaking it down in the rating algorithm, but if there's enough people that want to chime in that it makes it to the front page even after it's been covered before, removing it entirely seems fairly heavy handed.

On HN, a story is considered a dupe if it has had significant attention in about the last year. We bury those, i.e. move them off the front page. If we didn't do that, the HN front page would quickly fill up with repeats, especially the most controversial repeats, which never run short of people wanting to "chime in".

The present case is especially clear cut because there were two major recent discussions of the story.

Fair enough, and I actually thought the top result in the search was this story the first time, so thought it was last discussed six months ago, not that and just a single month ago.