Google access to information can be used for evil. But it takes only very small step to have the same thing reclassified as good. Take your example and let's say some eager attorney general declares war on obscenity, gets some laws passed by bleeding-heart think-of-the-children lawmakers and asks Google for data, which Google can not and will not refuse since it's not for evil - it's for the ultimate good of the children! And bingo, you just facilitated totalitarian state, where all you do online is now recorded by the government and can be used against you if they dislike it. And with the best intentions.
Let's face it, "Don't be evil" is nothing more than PR. Great PR, but still nothing more. Very few people actually do something they think is evil. Usually they only do what they had to do, or what they were ordered to do, or what the situation made them to do. And I have absolutely no doubt Google will do the same, and will if needed find reason why anything they do is not evil. Any of us is capable of it and Google is no exception.
Let's face it, "Don't be evil" is nothing more than PR. Great PR, but still nothing more. Very few people actually do something they think is evil. Usually they only do what they had to do, or what they were ordered to do, or what the situation made them to do. And I have absolutely no doubt Google will do the same, and will if needed find reason why anything they do is not evil. Any of us is capable of it and Google is no exception.