MUN= Model United Nations, an extracurricular activity where students simulate UN councils and such. Tim Sullivan founded it with students and really fostered agency through it.
And yes he was extremely impressive in his openness and listening. There was also President Gerhart (I spoke at his memorial but can’t find the speech now) who was like that…he had lunch w students! Both of them together was the golden age of AUC IMHO and I am lucky they were both there when I was a student and when I graduated