What Bollinger did was exceptionally rude. Poisoning the Well. Mahmoud, as much as I dislike him, had reason to be offended. He was set up, to put it bluntly. Perhaps he expected it.
Bollinger could have saved his remarks for the end of the session, in the summing up, rather than invite him and then publicly attack him in an academic setting. The Q & A was sure to expose Mahmoud's rubbish, and anything missed Bollinger could have covered in the summing up.
Bad form. For all that I don't care who takes the piss out of Mahmoud the Mouth, this was not well played.
For clarification: I am hardly "a liberal" but I generally agree with Thomas C's sense of what was wrong.
ETA: Dear Cello Man and sackett. President's of prestigious Universities are supposed to be classy people, and what Bollinger did, in terms of style, was gauche. The summing up was a perfectly good time to point out Mahmoud's duplicity, once the collegial discussion and Q & A that He Was Invited To Come For as a Guest of The University, was complete. The substance of Bollinger's points was solid enough.
DR