You don't have to participate if you don't want to. And, no, it won't cause you to get kicked out.
However, most MBA students realize the value of promoting their school because the better their school is, the higher the value of their degree.
Furthermore, media promotion experience is something that adds value to your personal profile (ie, your resume). It may also gain you networking opportunities.
MBA programs need their students to participate in these kinds of activities because prospective students want to know if they'll be a good fit at a particular school. They want to know who their fellow students will be, who will be teaching the courses, who will they be working on teams with, etc.
15 Years as Director of MBA Admissions - Now Working For the Applicants as the MBA Admissions Coach
Wendy Flynn is the MBA Admissions Coach, providing comprehensive MBA admissions consulting services. As the former Director of MBA Admissions for 15 years at a top-30 MBA pgoram, Wendy holds deep expertise in admissions issues for Full-Time, Executive and Professional (Part-Time) MBA Programs. Through her blog, MBA Expert Insights, she brings the view of the Director of MBA admissions to MBA applicants and others.
MBA Expert Insights Blog: http://www.mbaadmissionscoach.com/blog/
Member of the AIGAC, Association of International Graduate Admissions Counselors