Dude, I literally ran a Firefox plugin at one time that gave me the "Great Firewall of China" experience. But just in case, I went over to Baidu and did a search and here's the official story you speak of (and the only one told in the search results): https://www.chinadaily.com.cn/opinion/2011-07/14/content_12898720.htm
The article does not address how many people were killed or even whether violence occurred.
I would call those results to be censorship.
Edit: I don't like the South Korean state either, but not more or less, just different. I'm not here to say which state is more morally justified than another, even when they're at end stage capitalism.
Well now that we have established that it is as censored as I believe because I have first hand experience, can we circle back to massacres and censoring said massacres are bad and not what we want in a social media service?