jsnell's answer is correct.

We restore these things when we see them but sometimes someone needs to tell us about it! the way to do that is hn@ycombinator.com. (Someone did tell us in this case.)

It probably triggered the flamewar detector (a lot of comments, not a lot of upvotes). Not surprising given what a horrible title the other post has.

IIRC HN has some sort of flame war heuristic and when comments outrank votes on a submission it gets deranked. Which is kin of unfortunate if it's just ordinary discussion.

HN algorithm is weird. I think it's moderated with manually inserted weights.