Instead of trying to interfere in states' elections, the GOP would be on firmer philosophical and legal ground if it just expressed to the residents of those states that they were diluting their own votes with such choices.
If they decided it was worth it, then hey, so be it. They're their votes to use as they wish.
@Mikerotch75 if you're referring to the Electoral College voting for president, that's a different issue.
Either way, it's a political and legal issue, not a moral one.
@volkris @TwistedEagle I see no ethical issues with changing the electoral vote formula to only count legal citizens.