The issue comes up frequently enough, although I don't believe that question was certified in the current case mentioned in the OP. I do however see that some of the amici curiae briefed the issue extensively, as have other parties before them.
It's worth noting that respondents in this case (i.e., the original plaintiffs below) have staked a substantial amount of
their argument on the Enumerations clause, arguing that "The Constitution requires an 'actual Enumeration' of the population [and]
enumeration must count all residents, regardless of citizenship." (Brief of Respondents at p.2.) That argument actually lost in the district court, as
petitioners point out, but respondents somehow believe that the current SCOTUS affirm on that basis. IMO, this was a tactically stupid move, because Petitioners did not raise that issue in the
petition, and but for Respondents' brief, the SCOTUS would have no occasion to consider it. As I pointed out earlier in this thread, the question of whether "persons" refers to citizens in the Enumeration Clause is technically an open question. Unless the Court dodges Respondents' "Enumeration Clause" arguments entirely (as they may, because the question isn't certified), the Court must address whether unlawfully present persons may be counted in the census, and thus used to apportion seats in Congress. And if they do address that issue, I think we can all agree that they are unlikely to be sympathetic to Respondents.
