This comes down to the difference in underlying values of different cultures. Forcing what you think people should want onto others when it's not what they really want isn't effective, even despite your relative moral justifications. There are ways to accomplish notifying the user of censorship which isn't shoving it in their face.

Users simply won't use Google if it's beating them with a stick to remind them that websites are censored and that users should use a VPN. Chinese citizens know about the censorship and most, outside of specific provinces, simply don't care. Those who do already use a VPN.