Although I have troubles rationalising it I feel like this would be wrong. Should a citizen abroad not be able to vote on how these kind of people are treated (social services, taxes and such)? Some country do not allow dual citizenship but I don't think I like this idea either. Some places restricts some privileges if you don't live there atleast a few months out of the year so this could potentially be a way to implement it. You can't vote in an election cycle if you didn't live there atleast 3 months or something. But then again this won't prevent weaponizing democracy. All in all it's a very complexes situation that warrants a serious discussion.

P.S not a US citizen