That would all be more reassuring if the Census Bureau hadn't assisted in rounding up Japanese Americans during WWII. Whether or not intelligence agencies track minorities now is irrelevant. If Congress ever decides all Arab Americans, or Japanese Americans, or Mexican Americans, or any other hated minority de jour, are a threat to National Security, they'll repeal the laws protecting census data again, and the FBI will have those records within days.
This threat is obvious to everyone who supports the Census. That's why the laws were created - to establish the principle and tradition that Census data is sacrosanct, and ensure that nothing short of overt repeal (such as interpretations, regulations, policies, executive orders, politely worded requests, or FISA orders) will unseal the files. If we breach those laws in the midst of a perceived crisis, especially without punishment for the violators, we are essentially giving up the opportunity to have honest Census responses for several generations.
> If we breach those laws in the midst of a perceived crisis, especially without punishment for the violators, we are essentially giving up the opportunity to have honest Census responses for several generations.
After seeing the hysteria after 9/11, and the power of propaganda, I don't think that what you mentioned will deter people.