Two more articles/viewpoints, each with a distinct perspective.
Dershowitz (Newsweek): https://www.newsweek.com/university-chicago-requiring-loyalty-oaths-its-faculty-opinion-1532685 Focuses on the statement itself rather than the restriction to Black Studies and questions the impact it would have on academic freedom.
Inside Higher Ed: https://www.insidehighered.com/news/2020/09/16/university-chicago-english-faculty-prioritizes-black-studies-graduate-students-2021 Focuses on the restriction to admit Black Studies. The number is, indeed, 5 as others have pointed out, and this results from their funding model and the number graduated the prior spring (five in this case).