This mindset is a pretty convenient way to absolve oneself of any guilt felt over what that service you're offering is contributing to. I also find this reasoning reductive and cynical, for what it's worth.
It doesn't absolve you of guilt whatsoever. If you're feeling lots of guilt over what your employer is doing, then you should resign. There are absolutely companies I would never work for because I morally disagree with what they're doing. Google is not one of them.
I was being pretty sarcastic with my comment, I agree with you, that mentality does not absolve anyone of guilt. I meant that thinking in those terms inoculates the person from feeling the guilt they absolutely should feel over contributing to evil.
They don’t feel any guilt, the transaction abstracts them of any.