You know, I think they're kinda missing the whole point. Or maybe not. I find it hard to believe that anyone could be that dense -unless it was on purpose.
Yes, the population of "illegal aliens" would increase. But that's only because their kids would no longer be considered citizens. And I doubt they have any way to include the drop in illegal immigration that would likely result from this.
I personally don't have a dog in this fight. My beef concerning illegal immigration is the entitlement programs. And that's not in any way exclusive to illegals. There are plenty of "citizens" who are living on the productive public's dime, too.