[pmoriarty]

"the data should be treated anonymously"

The problem is "anonymous" data is often really easy to de-anonymize, especially when there's so much unique, identifying information there, as there is with the census.

Even if it did somehow manage to remain anonymous, they could still tell that a person with some undesirable characteristics lived at such and such a location. That would be enough to round people up. They don't necessarily have to know your name.