The Hacker News ranking algorithm tends to penalize stories that address social issues. The Hacker News ranking algorithm does not penalize stories that address social issues. It doesn't consider social issues at all, apart from a couple of special cases that we turn off once a major wave subsides [1]. The effects the OP is observing are mostly caused by user flags and the voting ring detector. 1. The intention there…
I would be more fair to address the broader point of the post rather than just one sentence. It's good that the moderator(s) specify why something is penalized[0], but it doesn't really change the overall result. [0] As defined by the post in question.
On hot social and political issues, many people find it irresistible to conclude that HN is biased against the side they favor and favors the side they oppose. They perceive this bias in all things HN: the community, the software, the mods, etc. But the truth, as far as I can tell, is that on most of these issues the community is divided. That's why the threads on them turn into flamewars.
Users reliably flag threads that turn into flamewars on HN. (By "flamewar" I mean angry arguments over predictable positions.) Moderators do so as well, though not to the same degree. But this isn't a bias against social issues per se, let alone particular social issues—the same pattern holds on threads about, say, basic income, or high-frequency trading, or even something like static vs. dynamic typing in programming. It's a matter of how divided the community is and how strongly people feel. It's more noticeable on any issue where one feels strongly.
What I do think it makes sense to call the bias of the site is a bias against the low-signal/noise discussions that inevitably result when people angrily disagree, especially when they do so through the filter of a pre-existing ideological battle. This is biased in the sense that HN's guidelines are biased: they call for certain types of stories and discussions rather than others.
Sometimes people argue that HN should abandon its anti-flamewar bias, because after all these are important issues and they need to be debated. But this fails to consider systemic effects on the site. The more ragefires burn, the more thoughtful users leave. That selective process, repelling the users HN most wants and attracting those attracted to flames, is a vicious circle that (a) is hard to get out of and (b) would turn the site into scorched earth. For all HN's flaws, it would be nihilistic to just let it burn.
That doesn't mean we aren't open to ways of balancing these things better: they're hard to balance, and if we're missing something we want to know.