So in your view, because a minor can not vote, he's not a constituent? It's not fair for an elected representative to stand up for him? How about a 17 year old?

So in your view, because a minor can not vote, he's not a constituent? It's not fair for an elected representative to stand up for him? How about a 17 year old? How about a person who's in prison, and therefore can't vote (in some states)? For certain policy aspects, such as national security and defense, it absolutely makes sense to actively exclude and ignore the concerns of non-citizens. They are really not 'true constituents'. But for most other things, the person who's considered a constituent is a law-abiding, tax-paying person, not a persona non-grata (that would be the illegal immigrants aka 'undocumented immigrants' whose cause is taken up with gusto by both political parties); it is absolutely the responsibility of the elected representative to pay attention to his concerns.