Hmm that's an interesting point. However, much like a bank needs customers doesn't Google need users? I find it not very persuasive that withholding an entire continent of users would result in much more than an empty threat on Google's part. If Google can't service Europe, then Europe would develop its own services, much like China has, a terrifying prospect for both American foreign policy and Google's future prospects. Perhaps Europe would even turn to Baidu. I don't think that would happen, but the threat would be alarming to Google's negotiators.

EU law considers a citizen's data their personal property (akin to a bank holding a citizen's money), and Google is holding a lot of it. Google could get into significant additional legal trouble depending on the method they chose to withdraw their services.