It's absurd to say that slurring "the general attitude of Chinese people" was civil, polite, and on topic. If you say that, I can only imagine that you're not coming into contact with the very large numbers of people who would find such a comment to be the opposite of civil and polite. That's not our situation, and we have to take care of all HN users. Everyone has the right to come here and not see their country or race or ethnic background (or similar groupings they may belong to) put down in that way.

Perhaps you don't feel like this matters, but I can tell you for a fact that people have been hounded off this site by comments of this nature (e.g. China-related slurs), including extremely ugly personal attacks. I don't want to have anything to do with a site where that happens, and I don't believe that the vast majority of this community would either. None of us wants that community. But we can easily end up with it anyway, if we're not careful, because that's how group dynamics work.

Part of the problem here is that the forum feels like an intimate conversation, and in intimate conversation there is more latitude for talking in a grand and speculative way about this stuff, especially if you have high trust from previous interactions. But when you post to HN what you're actually doing is broadcasting to millions of people. Public broadcasting has to have different standards. Imagine what would result if a million people heard the things that you (or I, or any of us) said to your friends, without any mitigating context.