Part of the rights of individuals is self-determination. If a people want to pick and choose who they admit into their community, that is their right. If they w

Part of the rights of individuals is self-determination. If a people want to pick and choose who they admit into their community, that is their right. If they want to close their borders to the rest of the world, that is their right as well. The fact that everything dies in the long run doesn't mean that those who hold their nations and cultures dear today should not work toward their preservation. An argument from nihilism isn't convincing to me. You and I will die too, but that shouldn't stop us from pursuing the good life in the meantime. Besides, it's not a given that all current nations and cultures will die. They will certainly change over time, but it could very well be that the first human colony in another galaxy will fly an American flag. It's unlikely, but who knows.