I am not an admirer of A'dinejad (or GWB) - however strongly feel against Columbia University president Lee Bollinger's actions.
It's not polite to invite a nation's president and be rude to the guest whilst addressing an entire faculty/university, that's just bad sermon. Bollinger's actions placed him quite low and undermined etiquette & credibility. There are multiple ways & tones with which to disagree. Columbia is a world renowned educational institution, not a public school for the juvenile.