If you follow China, you will know that part of their strategy is to be a unique voice in the world. Much of that rests upon China simply not interfering in an another state's internal affairs. They tell the world that unlike some nations (i.e United States, European Union, Canada), China does not interfere in the domestic policies of any country trading with her. This has often caused what Jiang Zemin (former President of China) advertised as "win-win" relations, however their are cases where China's interests were not necessarily in line with the people of a given area's interests.
It sounds like something from Star Trek's Prime Directive, I know. The Chinese position, on the surface can sound ideal. And, indeed there are many countries that have really benefited from the Chinese "win-win" policies. But, there is a far more sinister aspect to that policy as well.
To be more specific, China openly and notoriously partnered with the Sudan in order to purchase oil from them. Groups in the Sudan (with government participation and knowledge) have been launching a genocide against black tribes in the Darfur region. Most of the world was united in condemning the genocide and they fought really hard to even have the genocide designation applied (when genocide is declared, the U.N has a legal duty to intervene, so they don't like to use the world 'genocide' very often). The Sudan was able (and still is) to murder all the young men in entire villages and impregnate the woman through rape because one particular nation was willing to close their eyes and ignore the "internal issues". That nation was China. China simply refused to interfere.
China does intervene in cases where they look really bad to the outside world, as has begun to happen in Darfur, but also in Burma. In Burma, China has pressured the government to get control of it's HIV crisis and drugs which are pouring across the Burma/China border. In that case, China's domestic interests line up with what is good for average people in Burma. But, China's intervention in that matter was simply out of her own good. China needs stable borders.
Now, I don't want to go on and on about all of the examples that come to mind (there really are many) of when China has or has not intervened for humanitarian reasons, except to point out that they very seldom do intervene. They proudly state that they do not interfere in other nation's business. But, there is a dangerous side to this for Beijing, and I think some of that is already being seen.
The world is now getting used to a re-engaged China. Yes, China was (for almost all of history) the most powerful nation to exist. Very little in Europe can truly compare to what China has almost always been. They took the 19th century off from dominance but now, in the past two decades they have shown that they are truly back. Today, however, we have a very tuned in world. People are well aware of China as a major world player. As such, China's activities do not go unnoticed and China will suffer some "blow back" for their activities world-wide just as the United States does.
In his book (Charm Offensive), Joshua Kurlantzick points out that in some cases local people have already been so enraged by Chinese support for their corrupt governments that they've attacked Chinese business people on the streets, or have attacked their place of business.
This could just get worse for the Chinese if those countries do experience "regime change". How would a newly free Burmese people feel about the country that enabled those who murdered their men and raped their woman and children to prosper? How will the various Black tribes in The Sudan view China?
China does not want to interfere in the domestic affairs of another nation. Admirable in theory, but in practice we can see that it often alienates the citizens of those countries from China. China's interests would be better served by operating with other nation's to get tough on the worlds most brutal regimes. China would add legitimacy, and be viewed positively if she were to work through the U.N to improve life for the people of some of these regimes.
China has an interest in building up good relations around the world, and if China wants to take a long view they must realize that sometimes it is better to intervene...if only for selfish reasons.