What is with the American universities? You invite somebody to speak at your college and then you insult them or you throw paint bombs at them. Wonderful, gentlemen, I can see all that education to turn you into good citizens is so good. Truly these people are barbarians, do not even know basic rules of civilised discourse and debate. Then again, when the teachers (the University President...) themselves behave in this manner, are we supposed to be surprised if the students follow suit?
Irrespective of the motive, this was basic bad manners, reflects very poorly on the university and their parents. How would these students like it if I was a guest lecturer there and threw a bucket of warm spit over them if they answered a question badly?