The issue is there are limited spots in higher education, and when those students from outside the country come here it takes a spot from a person inside the country. Normally, I’m OK with that (I’m not anti-immigrant or “they’re taking our jobs!!”), but most of those students immediately leave the country once their education is done, taking that knowledge and training with them instead of staying here and contributing to the US. Many of these universities are also state-supported, so my taxes pay for them. Yes, the out-of-country students pay a lot more than in-state people, but they don’t pay more (or not much more) than out-of-state but still US students. My taxes are going towards helping to educate Chinese scientists who are actively working to attack the US. Also, a lot of critical research is done by universities and sponsored by US companies. This knowledge is immediately sent back to China on the cheap, since they aren’t beholden by our IP laws.
That said, it is discriminatory and is open to abuse. I don’t know which countries are on his “countries of concern” list, and I don’t know how easy it is for FL to add a country like Egypt or Ukraine or DRC to it.