.... Chinese didn't try do anything. ISP's elsewhere mistakenly configured their servers to use Chinese DNS servers.
Not quite accurate. The Netnod server 'causing the problem' claims to have and be serving proper information, but the Chinese instance of that server is having it's data stream filtered by China (on the presumption that nobody outside of China is getting information from that server). The problem arose when a couple of high-volume servers (one, or more, in Chile and one, apparently in California) got their root query packets routed through China and ended up filtered the same way that internal-Chinese queries get filtered.
To solve that problem without having to wander through layers of Chinese technical and political bureaucracy, the easiest solution was for Netnod to simply 'turn off' routes to it's Chinese server until the relevant Chilean and Californian routers get less problematic setups.
The root of the problem (if you'll allow the pun) is that China is silently hacking data from legitimate root servers that go through their systems. Normally this only affects users inside of China but, in this case, part of 'The Great Firewall of China' leaked out into the rest of the world.