Practically, I'm not sure that can even be enforced, or that Google has any incentive to enforce it. If a site uniquely tags each user via custom variables, or by sending users to a unique resource/goal/interim URL, will Google detect this and obscure/destroy the resulting data? Or is such tracking for the site's own purposes a core feature of GA?
And Google often has its own PII about the same user, from other visits to Google's own sites, anyway.
[1] http://www.google.com/analytics/terms/us.html - section 7 "Privacy"
https://developers.google.com/analytics/devguides/collection...
You need barely any information to construct a personally identifiable profile. The fact that you as the user of google analytics can't do it says nothing about googles ability to do it.
http://arstechnica.com/tech-policy/2009/09/your-secrets-live...