Maybe, consider it a difference of how I view representation. These people are here whether you like it or not, and they are vital cogs in the economy, whether you like it or not. Representatives should represent the people in their district, undocumented or not.
I am not trying to start a fight on this, but I'm legit curious: Is there evidence to suggest that having non-citizens as neighbors makes you more likely to vote in a way that represents the interests of non-citizens? Has this been studied? Because even if you are apportioning seats based on total population, it's only the actual citizens of voting age in those districts who are doing the voting.
What if, hypothetically, the evidence actually went the other way?: That living near non-citizens made people more racist, and therefore more likely to vote in representatives who advocated policies that non-citizens didn't like? Would that change the calculus?
I wonder if this question is similar to ones about white people's views of racial minorities. If I recall correctly, white people tend to be most biased in places where there are almost no minorities, and in places where there are a lot of minorities. There's basically a sweet spot of minority population where white people can feel proximity to minorities, feel like they're part of the community, but also not feel like they're being overwhelmed.
I'm not advocating this, it was just my read of the studies. I'll see if I can dig some up.