My guess is not that it's been censored, per se. I believe that it's been contextualized by the government in a way that's out of alignment with the way the rest of the world views that event. Outside of China, we view that as a symbolic event of an unknown, brave individual standing up to an oppressive government. Inside China, it's likely seen as a relatively inconsequential event. Their reactions to my interest included both "what event are you interested in?" or "why are you interested in that event?"
I don't think this is unique to China and I think it happens to some extent in the US. I think people, especially the right wing Republican voters, are shielded from the viewpoints of the rest of the world on many topics. Having been outside the US for almost the entire election cycle, I don't think most voters in the US realize just how much Trump is ridiculed outside of the US. In the US, the comparison with Clinton is roughly 50-50. Outside the US, I've yet to meet one person who doesn't believe that Trump could be a serious choice. There's recognition that Clinton isn't perfect and we should have nominated someone better, but there's general consternation that our country could have made the choice that it did. Granted, I've been mostly in Asian, Muslim countries where Trump's rhetoric about Muslims has an even greater ring of ignorance to it. But the US media has contextualized a lot of what went on in the election cycle very differently from the way the media in the rest of the world has.
The difference, of course, is that the recontextualizing in China is at the behest of the Chinese government. It's disturbing and dangerous no matter how it happens. But it's undemocratic when the government is the one doing it.