We sometimes close threads to new accounts when the situation is overwhelming, but I wouldn't want to do that in a case like this. Generally on HN, we try to err on the side of privileging positive contributions rather than filtering out negative ones, and we rely on community moderation and moderator moderation to try to dampen the latter. It only works partially, but it's better than punishing the positive contributors, and definitely better than being a closed community.
Kind of says something when this is seen as an exceptional case, given that a significant majority of people aren't white men...
You mentioned that this was seen as an exceptional case. It is exceptional. The vast majority of americans are white or male.