No, he is not. The State Department can revoke his visa at any time if it is determined that the foreigner is harmful or dangerous to America or her citizens.They are entitled to a hearing in immigration court. Not sure if he's waived that right by filing in District Court in NY
In the case of the antisemite the leftists are defending, he is drumming up support for an antisemitic organization and inciting more antisemitism at Columbia. He is harmful to Jewish students.