People also don't generally comment on the amount of pro-US or pro-Europe comments in those threads. I don't think I've ever seen any accusations of Western astroturfing. Influencing the media, sure, but not being directly in the comments.
Also, the US is trying to maintain a moral high ground (real or perceived). They don't want to be associated with China. I don't think anyone would say "well China does it too!" but they would absolutely say "well the EU does it too!".
I do think China gets dinged for their misdeeds more than other nations do. I don't see nearly the anti-India sentiment, despite the similarities. India is perceived as a country that makes some missteps on their way to modernization, while China is perceived as a country that's rotten to the core and making intentionally terrible choices.
I don't support China. I wouldn't want to live there. I just think that we're either mentally over-prosecuting China, or that we're giving more democratic nations a pass on their misdeeds. India still has castes, and didn't they just have a series of internet blackouts to suppress dissidents? The whole thing with the farmers, though I could be misremembering. They're democratic though, so we're all pretty sure they'll find their way. No one seems to consider that perhaps China will find their way as well. Germany had Hitler 80 years ago and they're doing fine today. Perhaps in 80 years China will be more free as well.