In this specific case, the claim seems to be less one of privacy and more one of "intellectual property." Gonzales doesn't claim that Google peeked through his window and saw him writing down notice of that 1998 auction. He acknowledges that it was, at the time, a publicly reported event. He's just claiming that now, 16 years later, he "owns" knowledge of that event and is entitled to control it, while Google doesn't and isn't.
Read the whole thing if you're interested.