I don't know if there is any way to protect against bots these days (other than something Worldcoin-like), which is a pity as I think HN is now overrun with them trying to inject anger and negativity into its Western-leaning audience's thoughts.
We are long past that being a means of distinguishing a bot for anything other than obvious crypto scams. I have no doubt at all that a substantial number of HN posts, especially on divisive topics such as this one, are made by foreign agents. HN is an ideal means of targeting the types of people driving Western economies, and so I am certain that it is one of the top targets for such operations.
The purpose of this attack was to normalize vigilante murder (and, as you say, the target was well chosen to achieve that). The division and societal breakdown come later when vigilante actions become more common.
As an example of how pushing a message too hard can have the opposite effect: In "The Last of Us" (the series, I haven't played the game) the bad people are white (and are especially bad if they are also Christian), while the good people are generally some combination of black, homosexual, and "neurodivergent". Three of the four groups we meet are led by women. The two good ones are led by black women. The only group doing well is a communist commune. When I feel like I am being manipulated I not only discard the message, but actively rebel against it.
Donald Trump disgusts me, but it feels to me like he at least authentically represents a viewpoint.
The racial composition of characters in The Last of Us series is the same as it was in the game, released in 2013 before identity politics was even on the zeitgeist.
I say this as a straight non-religious white man who is disgusted by Trump and the fact that people support him.
Making the main character and his brother hispanic is not "the same" as the game, especially when the remaining straight white non-hispanic men in the show are absolutely awful.
Or take the US version of The Office, where the one Christian character is a running joke, an awful person with terrible takes not meant to be taken at all seriously. Can you imagine how it would've gone over if the one black or hispanic character on the show was just a running joke?
