The move comes because of China's involvement with the government of Sudan and its treatment of its own people in that country's Darfur region. Although China buys two- thirds of Sudan's oil exports and in return sells weapons the Sudanese government seems to use mostly on its own people, it does just about zip with that influence to at least slow down the Darfur massacres. There's also Sudan's lovely focus as a marketplace for trade in human beings, but what's a little slavery among buddies?
You'd think a nation that has so many people might show some respect for them, but you'd be wrong. The Tiananmen Square massacre may be the best-known of its recent crackdowns, but the Chinese government allows its people few freedoms and enforces its control. While no one can deny China's importance to the world and the need to engage it in a responsible manner, you have to look for awhile to see some of those engaged with it use their influence to try to bring some change. Maybe if more did, or if more decided not to be used by a government that is more interested in looking right than doing right, things might change more quickly.