USA does not want to train scientists from other countries, who come home and can use that knowledge against interest of US companies, as a competition, or security. There are vast areas of science that are "double use". Will it help to keep stuff out of range of unwanted foreign actors? Hard to tell. Does it hurt USA soft power, sure. So the net result is to be seen.

Anything that's "double use" is already treated with a distinct level of scrutiny.