I think this makes sense from a national security perspective (although I doubt there is any scientist coming from these countries who are working on sensitive projects, maybe except China). Since there is too much trouble to figure out who is a spy, might as well ban all of them for the moment.
I do feel a strong nostalgia about the globalization era between the 90s and the 2010s, when I spent most of my life. But I understand it comes to an end, and I'm going to spend my second half of life in a much more splintered world.