> Google modifying the content is not really the threat model most people care that much about You're right that's not the concern held by the people accessing

> Google modifying the content is not really the threat model most people care that much about You're right that's not the concern held by the people accessing the content, but the target here seems to be the websites who partner with Google. If I publish something on the web and another company wants to host my content (including caches and CDNs) and I expect many of my readers will access my content without ever touching my servers directly, I would absolutely be concerned about my content being modified where it's outside of my control. Seems it'd be a lot of trouble to track down and verify that it were happening at all since google could change content any number of ways or not at all depending on the individual making the request.