I think you misread (or, equally likely, I wrote unclearly). I'm not saying "if you take the article seriously, we'll have nothing but social justice stories". I'm saying that if you take the premise that social justice is inherently interesting to hackers, then we'll end up with nothing but those stories.
Many people here, myself very much included, get their social justice stories in a different section of their RSS readers. It's not that those stories aren't interesting; it's that they simply aren't Hacker News, any more than updates about Girl Talk albums are Hacker News because hackers are so likely to listen to them.
I completely understand you don't want this type of article on HN. But, you don't need to worry the site will only be articles on social justice if hackers find the topic "inherently interesting." Most people here are inherently interested in a variety of topics and that's why the community makes room for a few these "off-topic" stories.
Broken window theory. The rate of civil rights outrages worldwide is more than high enough to overwhelm the forum, so the number of completely off topic stories only remains low thanks to people visibly objecting to them.
Acknowledging that social justice is inherently interesting does not imply that only social justice is interesting or that it is the most interesting. As such, the claim does not lead to 'nothing but those stories'. For that, additional premises are needed, none of which were posited.
Many people here, myself very much included, get their social justice stories in a different section of their RSS readers. It's not that those stories aren't interesting; it's that they simply aren't Hacker News, any more than updates about Girl Talk albums are Hacker News because hackers are so likely to listen to them.