And yet, people who don't trust the census and refuse to answer unnecessary questions are considered nutters, even with relatively recent historical evidence that the government can't be trusted.
If you don't trust the government with the census, it would seem more logical to just lie on the very first paper form that they send you. Chances are (very, very good chances) that they'll never send a human being out to check and thus will never know that you lied about whatever question you're uncomfortable answering.
It's one thing to noisily refuse to answer some question in order to raise awareness of some issue you have with the census, but if you think there's a conspiracy or that the government might use the information to round you up in the future, it doesn't make sense to attract any notice. Better to lie low, if you think that's a risk.