I do know the citizenship question was rejected. You brought it up.
I was just pointing out that of all the questions asked, it should be the first, not the last. "How many people are in your household?" Stop there?...we can talk about that. But, if we go further, then citizenship is the natural next important question. The Founders obviously intended to exclude resident aliens from figuring into representation in Congress. For example, the Constitution explicitly excluded "indians not taxed."
I suppose you could ask if the person is an alien and then ask whether they filed an income tax return since coming to the United States. If not, then don't count them. Sounds like a reasonable approach to effect the intent of the Founding Fathers. (I'm not trying to summarize liberal developments in the law, which I don't care to research. I'm just stating the intent of the Founders.)