Its because the requests aren't actually coming from China. China is redirecting worldwide users from Baidu to GitHub. Sorry, I don't have the link handy, but it was in that WSJ article on the front page.
I think you are missing the guy's point: what is the difference between Russian censorship and Chinese censorship? Github made a deal with Russia - why not also China?
Didn't know about that, that's make the difference. Usually in totalitarian countries everything is well documented as everybody want to put responsibility on someone else.