You hit that nail on the head. Nowhere on the form is it required that the respondent be a citizen, nor is the question of citizenship posed on the form. Any enumeration based solely on residency, (be it legal or otherwise), will skew the population figures and result in some districts having representation in Congress disproportionate to the number of citizens living in them, and the same will happen with population based federal funding.
maybe we can file to have it thrown out..10 years is a long time.