That argument doesn't fly, because our government can do most anything to a person outside the United States. Amd as soon as you realize that, you must admit that nationalities are important to the Context of the Bill of Rights. Ever heard of that law against assassinations we're bound to? Now that law wouldn't be necessary if the Bill or Rights restricted the US Government from "doing certain things" (Depriving life without due process) to persons without regard to political boundaries and nationalities.
You've got to understand the Context in which the Constitution exists.