A controversial Swedish internet surveillance law passed in 2008 allows the government there to intercept any internet traffic that passes Sweden's borders with no need for a court warrant. It's called the FRA law and the Swedes don't like it, and Google called it "unfit for a Western democracy". And the rest of Europe could start to get annoyed by it too when that internet traffic includes their Facebook data.
What I find the most interesting in this is what Google has said and done around the issue. As you probably know they opted to build a data center in Finland. I don't know if they ever even considered Sweden but if you consider the fact that the net traffic from Finland towards Europe and onwards still goes via Sweden, it doesn't really make a difference which they choose as far as the FRA law is concerned.
I'm guessing the proximity to Russia is the real reason for choosing Hamina. The rest feels like a clever Machiavellian way to play the "Don't be evil" card to me.