The term 'You are the product' carries heavier connotation than 'just the mind'.
Also in the case of Google it serves a brief span of your attention to advertisers. They are not engaged in selling minds, wholesale or in part. I have enabled Google Search ads on all my machines for this reason. This distinction is worth making, since in some cases, it is an algorithmic matching between buyers and sellers. This helps consumers discover products and services they need and advertisers to discover demand they may otherwise be unable to tap
For the moral argument, I don't think it makes a difference which part of a human's mind is the product.
This is like saying: "He didn't run him over - only his legs!"
Or, less drastically: "The whole program isn't full of bugs, just the Foo, Bar, Baz and Main functions."