From some old comments, I remember that there is a "voting ring" detector. (The details are obscure, because it's part of the secret sauce or something.)
I guess there is also a "flagging brigade" detector. [If not, I upgrade this comment to a feature request.]
Let's say you have 5,000 to 10,000 accounts who semi-regularly post as "normal looking" accounts with other activity, how many of those have to downvote/flag a post to knock it out of front page? Not many I gather.
Considering the upvote count even the hot rising posts on front page have. I would assume the flag threshold to be quite small. I don't know if each flag vote counts the same or does it depend on karma/account age, but at least from upvotes I would assume you would need less than 50 flags to pull even a hot story. So, paid influence ops should easily succeed in HN; whether they have even bothered with HN because of small audience size, that I don't know.
In most cases it is the politics aspect or the unfair coverage aspect that leads users to flag a story, like say on lab leaks; but this story being flagged so easily was interesting. It is about a tech platform intentionally/mistakenly censoring things we will count as free speech.
I guess there is also a "flagging brigade" detector. [If not, I upgrade this comment to a feature request.]