The Constitution is a restriction of the US government's power - that is always how it is interpretted and that is why I do believe the 2nd Amendment prevent gun control laws by the US government. Other governments never signed on to our Constitution. It doesn't not require the US government to affirmative promote those protections around the world.
My point was, if the right to bear arms is a right that goes beyond those just provided by the state (or an inalienable right), the Constituiton would prevent the US government from infringing that right to any person. It's not picking and choosing .
So, if I'm to accept your premise that the 2nd applies to citizens of other countries, then the entire Constitution must as well and we better get busy overthrowing dictators.
But then, I don't happen to think that the 2nd, or any of the Constitution, applies to anyone beyond our borders.
And our courts seem to think that way too.
However, it does apply to me, and we need to get busy overturning 70 years of un-Constitutional gun laws.