When Google left China they did so because they had "...evidence to suggest that a primary goal of the attackers was accessing the Gmail accounts of Chinese human rights activists."[0]
Since then, by Google's own numbers, the Chinese government has become significantly more suppressive and demanding: https://transparencyreport.google.com/government-removals/by...
Given the status quo, what message does it send to the Chinese government that Google is willing to backtrack on their statements and work with a government that is even more evil than the one they left? It's naïve to think that the Chinese government won't use Google's re-entry as a tool for suppression, and it's also naïve to think that Google doesn't understand this. Their greed will only further facilitate these human rights abuses.
[0]: https://googleblog.blogspot.com/2010/01/new-approach-to-chin...