Arizona’s three state universities are not difficult to get into, based on their automatic admission requirements:
https://admissions.arizona.edu/freshmen/admissions-decisions
https://students.asu.edu/freshman/requirements
http://nau.edu/admissions/getting-started/requirements/freshmen/
Presumably, the schools are large enough that, after dipping pretty far into the pool of Arizona high school graduates, they still have plenty of space to tap the out-of-state and international students for their tuition.
On the other hand, if the international students in question do not interact with other students (or faculty) much (as the author seems to think), they may do little or nothing to counteract what the author calls “the new isolationism”. At worst, if they show up but remain in their own isolated social circles, other students may be more prone to forming unfriendly stereotypes about them.