In late July, Trump officials announced they would investigate Duke over the criteria its student-run law journal used to select editors. They also accused the university’s health system of “systematic racial discrimination,” without citing any specific incident. Duke’s turn on the hot seat provides a window into how the administration’s priorities broadened in recent months, from a focus on antisemitism to efforts to stamping out diversity measures. It also highlights how the administration has sown confusion and fear in higher education as it chooses its targets — and its favorites. Even as the administration has picked out one set of...