There are few smart people left in the Trump administration

Blame Wilbur Ross's Clumsy Lies for the Census Mess

Most of the smart one left.
What Wilbur wanted to say was that citizenship is needed to count up the number of voters, a requirement of the Article 1 part 2 Here is the main clauses:

The House of Representatives shall be composed of Members chosen every second Year by the People of the several States, and the Electors in each State shall have the Qualifications requisite for Electors of the most numerous Branch of the State Legislature.

The actual Enumeration shall be made within three Years after the first Meeting of the Congress of the United States, and within every subsequent Term of ten Years, in such Manner as they shall by Law direct. 

And the 17th:

The electors in each State shall have the qualifications requisite for electors of the most numerous branch of the State legislatures. 

Counting citizens who can validly vote for representatives must the same qualifications as the most numerous state legislative branch, namely they must be citizens. It is built into the constitution.  It was never an issue, whatever the bonehead Wilbur says, we can mostly ignore, he is a idiot political candidate.

The real issue is California. Whites not allowed to vote,  illegal immigrants vote twice, and the Chinese are a special case, they get three votes.