A more positive-sum view is that the US is bringing the rest of the world up in science every time it exports a PhD.
While indeed a positive outlook, I think alot of Americans are beginning to wonder what the benefit will be to them. The isolationist and xenophobic rhetoric of recent years is mostly a reaction to a growing sense that increasingly few Americans are benefiting from global goodwill and development. While I dont agree with the sentiment, its not entirely incorrect to describe such relationships are parasitic more then…
I'm not sure I buy your claim that this is the reason for the rhetoric. And if you're right that this is the reason for the rhetoric, it's extremely flawed reasoning.