I'm honestly surprised they're required to abstain from doing so at the author's request.
You can only read the context of the match after finding the search result after all, not the whole book.
It's an example of significant overreach of intellectual property from how I see it. The robot.txt rational doesn't apply there either, as their scanning does not impact anyone's resources. And it's been published, which makes it public by definition.
They do (or did). They showed the text around the search term, around a page or so, which made it possible to reconstruct the whole book without that much effort.