We should welcome high intelligence foreign students in our private universities. It is really for the universities to balance their institutional priorities, and decide on the desirable level of foreign students, subject of course to any applicable laws regarding discrimination. If people do not want as many international students entering the country to study, they should agitate at the federal level to restrict student visas.
Public universities are a bit different to my mind. Citizens of a state have the right to restrict foreign enrollment at their state universities, but again the proper venue for this is through the ballot box.