Yeah, when most of your masters and PhD students are foreigners with a student visa, it's quite a risk for them to travel to the U.S.
Edit: I'm afraid this might be misinterpreted as a racist comment. So for clarification, I'm saying this because I know someone personally who works as a research assistant and lab manager at McGill university. At least half of the post-graduate students they work with are foreign students who are here on a student visa.
They're often invited to conferences all over the world. But recently there was a big one that was to be held in Baltimore. The professor who heads their department, and who is very active in that research community, initially thought there was nothing to worry about. But all the foreign students cancelled their trip out of fear. And over time it got so bad even the professor canceled the trip and the whole event is at risk of being canceled.
It's a really sad situation and I sympathize with these students, some of which I also know personally by having hung out with them and helping them out by carrying some of their stuff to help them and my friend with their work. These are important missed opportunities, especially to get their names out there and network with other researchers from around the globe.