Could you please not post in the flamewar style to HN? Especially not the ideological flamewar style? We're trying for something other than scorched earth here.
They're being completely civil. This does not at all sound like an "ideological flame war."
Racism in society isn't an ideologocal point. It's reality. They're pointing out facts that are uncomfortable.
If the "spirit" of HN is truly about intellectual curiosity around things that relate to tech and entrepreneurship, then HN needs to embrace the fact that society ultimately rules over all -- most certainly tech and business.
I fear that your comment here and re-direction to "the rules" is a censorship attempt because this is an uncomfortable thing go think about. Is HN a place where discussion about social problems that infect all of tech, business, and entrepreneurship not allowed? Is talking about racism "ideological"?
HN has been having lots of discussion about racism, just as the rest of society has been (or rather, societies, since many countries are represented here). If your question ("Is HN a place where discussion about social problems [is] not allowed") comes up, that can only be because of unfamiliarity with the history. If you want to get more familiar, HN Search is a great resource (see the box at the bottom of every page).
If you wouldn't mind reviewing https://news.ycombinator.com/newsguidelines.html and taking the intended spirit of the site to heart, we'd be grateful.