The University of Chicago has built a brand around the idea that its students should be unafraid to encounter ideas or opinions they disagree with.

To drum that in, the school provides incoming students with copies of its 2015 free-speech declaration, known as the Chicago statement, which states that freedom of expression is an “essential element” of its culture.

And the university has long adhered to a policy of institutional neutrality, which strongly discourages it from divesting from…