There is a real simple solution to the problem of disruptive students. Make it very clear beforehand, that any outbursts or other attempts to disrupt the speaker will result in expulsion from school. It happened at my school in 1966 at an ROTC review by anti-war students. Each student who took part was identified by photo and expelled for one year. All it takes is some guts on the part of the University. Like that is going to happen, right?