It's called "hacker" news for a reason.
But he missed the mark here. It feels like he published a first-draft without getting any dissenting takes on one of the biggest hot-button topics on the web. I (or a million other people) would have been happy to read a draft of this and explain that he'd create offense and confusion with his... attempt to explain the history of priggishness around social justice based on his lived experience... if that's really what this is supposed to be.
These people are willfully ignorant, but they're so arrogant that they think that they're right about everything.