p.s. as another poster added, your state department can give him an exemption to enter. But as it stands now, he cannot enter.
We can agree that Novak Djokovic did not get an exemption to play in the Australian Open but he will be able to get an exemption to play in the U.S. Open. That will be held on June 16–19, 2022. I see no reason why he will be denied from through customs.