Why does anybody do business with ANYBODY?

Usual totalitarian bashing aside, this may actually be the real reason:

Back ground info: Spring Festival is coming (this year it's Feb. 10th), which calls for all people to go home to unite with their family. And this makes the train tickets very difficult to obtain and the beginning and ending the holidays. The railway ministry in China has build an online train-ticket buying/reserving system (12306.cn) a couple years back and it is now well known when new tickets would be available online, and they sell out within minutes.

A while ago some Chinese programmer wrote a (naive) browser plugin to automate the ticket reserving operation. A few factors contributed to this plugin causing a lot of extra strain on the already burdened 12306.cn site: it would poll the site repeatedly if the service was not available; as it relies on some Javascript hosted on GitHub and it tries to load that repeatedly as well; the plugin is packaged in some binary distribution of a couple Chinese re-branded browsers which brags about it's ability to "help you grab the ticket".

As a result, it brought down GitHub a couple weeks ago (when the grabbing of this years tickets begin), and the ticket sellout windows went from minutes to seconds.

The railway ministry is pissed and claim that this practice is "illegal" or "immoral" and should be banned. Blocking Github could just be the attempt at blocking that "ticket assistant" plugin: No Github, no plugin.

refernce: http://www.techinasia.com/china-railway-ministry-asks-kingsoft-shut-browser-addon/

1,890,000 results on google http://www.google.cn/search?hl=zh-CN&newwindow=1&q=tianamen+square+massacre&start=90&sa=N
174 results on baidu.com http://www.baidu.com/s?wd=tianamen+square+massacre

yes, that's right, 174!
there is a line on the google result page that says:

'In compliance to the local laws and regulations, some search results are not displayed"