The thread reached the top of Hacker News, then went to #15. It spent 5 hours on the front page, which is a lot longer than it would have if the topic hadn't been YC-related. See https://news.ycombinator.com/item?id=41732846 for more.
The article only states that the post was deliberately lowered in the rankings to reduce its visibility. "Is this true" ? What your explanation is hinting at, although you're not saying it outright, is that "Yes, that's true." The graph posted below speaks for itself.
If you (or anyone) wants an accurate view, you can't just look at one graph. You need to take into account that moderators are downranking stories on HN all the time. HN is a curated site (https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...). If we weren't downranking stories all the time, the frontpage would be completely different—like a garden when there are no gardeners weeding it. The site would basically be all drama, all the time.
That article was of the type that we'd normally downweight off the front page, since it wasn't substantive or intellectually interesting in the way that the site mandate calls for. Since it was about YC, though, we cut the amount of downweight. The post went from #1 to #15 instead of (say) #55 or whatever. #15 on HN's front page is far from "disappeared". It's still a prominent position, and the post continued to receive a lot of attention and traffic that it otherwise would not have.
> What your explanation is hinting at, although you're not saying it outright, is that "Yes, that's true."
I wouldn't say so. The reason for downweighting the post was that it wasn't a good article for HN. The reason for downweighting the post less was that it was about YC. You can call that "deliberately lowered in the rankings" but it's equally true to say "deliberately heightened in the rankings". It depends on which baseline you're comparing to. Relative to the baseline of standard practice on HN, the post was heightened, not lowered.
Is that clearer? I'm not asking you (or anyone) to agree with, like, or approve of how we moderate HN but I would like the details to be understood.