All of which is totally irrelevant to the whether current trends in international law should play a role in interpreting the U.S Constitution as espoused by Stevens,Ginsburg and O'Connor. Fundamentally, it is an issue of national sovereignty.
I don't share your belief that US law is in a bubble. Even the vocabulary of the Constitution is derived from the concepts of long established legal codes not of domestic origin. This is a tempest in a teapot and of no real concern.