I agree that there's no point in arguing with low-quality comments, but for different reasons.
The other kind of comment that predictably appears in threads about China are suspicions that astroturfing is going on. When dang bothers to respond asking for proof, it usually later turns out that the comments in question were made by completely ordinary members of the community who happened to voice a dissenting opinion. (Those kinds of accusations are against the guidelines, by the way.)
There is also not just one group making such comments, but at least two different ones:
The first are all about whataboutism. Whenever the topic is the Chinese government doing evil thing X, they start talking about the US government doing something similar to X. Those people are highly likely to be US citizens (their obsession with US politics is a strong hint) and they only use China to segue into the topic they're actually interested in discussing.
The second are Chinese cheerleaders. They think that China is overall on the right track and point to rapid economic growth as proof. You don't usually see them in threads about Chinese human rights abuses (because even they agree that those are evil), but in other cases, like here at the bottom, they make an appearance. There's no need for the government to pay those supporters, because the natural supply of nationalist types is large enough.
There is a third kind that's easily confused with the second. Some people will agree with specific developments because they feel that the previous situation was even worse. For most people, Google censoring search results would be a bad thing, because for them the change is (uncensored Google -> censored Google). But for Chinese people who see the change in terms of (censored Baidu/Bing -> censored Google) it's still an improvement.
Then there's a fourth kind on the opposite side, for whom everything about China is connected to everything else. They're somewhat of a mirror image of the first group; instead of using China doing X as a prompt to talk about the US doing X, they'll talk about China also doing Y and Z instead.
I think none of those trends are much to worry about, though. Although HN voting on political topics tends to be quite a bit noisier, well thought-out responses are still more likely to end up closer to the top than to the bottom.