So what doesn’t the “Commerce Clause” allow?
To be quite clear the census clause does not require it. And the Fourth Amendment’s “The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated” is quite strong in suggestion that the Federal Government has no permit for asking such intrusive questions.
The Commerce Clause is the dominant law.
The ACS is not an unusual search under the Fourth Amendment. You are not being penalized for any answer you give to the Census Bureau.
Modern societies need this information; I know from having been there that the identifying information is stripped from the ACS. No one who gets the data knows from whom it came from. It may be annoying but it’s not unconstitutional. Sorry.