I don't know where you get the idea that the purpose of the Constitution is only about how the government functions. It is clearly the majority of the Constitution, but plenty of the Constitution is about what people (American citizens) can or cannot do. Constitution says you have to be eighteen to vote, you can't own slaves, and you can't sell booze from 1920-1933.
I think a lot of people are viewing the Constitution how they want it to be (a set of ideals about liberty and even then only the ideals they espouse) and not what it is (a legal document with centuries of practical use). You can say America is not being moral actors about how they are treating foreign people who don't live within its jurisdiction, but the Constitution has very little to do with this issue. To say it does is cherry picking what you like about the document without acknowledge the realities of it.
I think a lot of people are viewing the Constitution how they want it to be (a set of ideals about liberty and even then only the ideals they espouse) and not what it is (a legal document with centuries of practical use). You can say America is not being moral actors about how they are treating foreign people who don't live within its jurisdiction, but the Constitution has very little to do with this issue. To say it does is cherry picking what you like about the document without acknowledge the realities of it.