I'm surprised that the author could write such a cherry-picked article with a straight face. I clicked through to the six links in the twitter comments. Here's a summary of who made them:
1. bobcostas55: member for 146 days, 42 karma
2. gph: member for 997 days, 634 karma
3. lulzwat1111: member for 32 days, -8 karma, comment downvoted into oblivion
4. aianus: member for 588 days, 369 karma
5. https://news.ycombinator.com/item?id=8372411 I honestly don't see the problem here?
6. nickthemagicman: member for 690 days, 241 karma, comment downvoted into oblivion
For context, I have over 4500 karma (I only comment a few times a month and don't submit much), and the HN user with the 100th highest karma has over 16,000. In other words, these comments are not representative of the entire community, or of even a single medium-profile user.
The vast majority of the time, ignorant comments are met with multiple replies setting the person straight, or with downvotes (as I do, for anything that is insulting or offensive).
Hacker News intends to attract a technical audience. The community includes a wide variety of people, some of which are 16-to-25-year-old men who have poor socialization skills. Some of them (and some others, certainly) have naive, twisted beliefs, or they are just unaware of their privileged position in society. Others are from different countries that have old-fashioned gender norms.
I don't think this is a problem unique to HN or even to tech. I claim that you could just as easily write an article like this about fraternity or country club communities, if their communications were indexed for the entire world to see. At least in the case of HN, you have a large number of dissenting viewpoints.
I actually think it's good that short-sighted individuals express their bigoted views. It gives others a chance to provide them with some perspective. Even more, though, prudent individuals who think the same thing have the opportunity to have their viewpoints changed as well. Also, seeing the extreme version of one of your views can cause you to pause and reconsider it.
Personally, I was quite libertarian and lacking in perspective on several issues (e.g., end user empathy, social welfare, the importance of tact) when I joined Hacker News 7-1/2 years ago. Of course I can't give all the credit to HN, but it has definitely had some positive effect in improving my personality and broadening my perspective.