We want them to see that they helped the Chinese police to jail people, human beings.
We were sure the case of Shi Tao, who was jailed for 10 years last April on the basis of Yahoo-supplied data, was not the only one. Now we know Yahoo works regularly and efficiently with the Chinese police.
This way, any request from the Chinese would have to be supervised by ... American justice. They shouldn't comply with all Chinese demands. It's possible to negotiate with the Chinese authorities. The Chinese wouldn't ban such an important company.
Rather than accept everything the Chinese authorities says, the big players could find a common position saying they will stick to the Universal Declaration of Human Rights and their own values.
This is a real shame. When a search engine collaborates with the government like this, it makes it much easier for the Chinese government to control what is being said on the Internet.