If it applies to everyone, we can overthrow Castro, the Iranian mullahs and the Chinese Communists tomorrow.
And we didn't need any reason to oust Saddam. It's right there in the Constitution.
If the 2nd applies to everyone on earth, so does it require the U.S. Government to provide everyone on earth with a republican form of government.
Or maybe it just applies to U.S. citizens and it takes an act of the Congress to authorize taking on a foreign country.
You don't get to pick and choose which parts of the Constitution you get to enforce.
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 .