1. An invitation to Ahmadinejad to Speak at Columbia was withdrawn in 2006 (see above). So why was he welcomed in 2007?The answer may be found in one of the links you supplied. Here's what the situation was like in 2006:
QUOTE
The dean of Columbia's school of international and public affairs, Lisa Anderson, had independently invited Mr. Ahmadinejad to speak at the World Leader's Forum, a year-long program that aims to unite "renowned intellectuals and cultural icons from many nations to examine global challenges and explore cultural perspectives."
In a statement issued yesterday afternoon, Mr. Bollinger said he canceled Mr. Ahmadinejad's invitation because he couldn't be certain it would "reflect the academic values that are the hallmark of a University event such as our World Leaders Forum." He told Ms. Anderson that Mr. Ahmadinejad could speak at the school of international and public affairs, just not as a part of the university-wide leader's forum.
(Bold added for emphasis)
In 2006 it seems that the decision was made that he could speak at the University, as he did in 2007, but that he should not be a part of the "World Leader's Forum," which would seem to be a special event, open only to those judged to "reflect the academic values" of Columbia. In other words, a lot of people can speak at Columbia, but very few people can speak at this special forum. Seems like a reasonable decision to me, in both 2006 and 2007.
2. Did this give a madman a forum in the US or was it productive in some way?I tend to think that it never hurts to listen to those who oppose you. At the very least, it confirms your worst opinion about them. In this particular case, Ahmadinejad's absurd comment that there is no homosexuality in Iran was very revealing, and quite properly exposed him to mocking laughter. After such a statement, who can take him seriously?
By the way, it might be a good idea to distinguish between those who are genuinely insane, and those whose thinking is imprisoned by religious ideology. Reading the transcript of Ahmadinejad's remarks in like reading the remarks of any other religious fundamentalist.
3. Is Columbia fair in who is allowed to speak there or is there political bias at work?Since Ahmadinejad seems to have provoked a very negative reaction with his talk, I can't imagine that Columbia was somehow biased in his favor. Rather the reverse, if anything. ("Let's listen to this guy talk and laugh at him.")
Hunter's threat to cut off funds to Columbia is an empty gesture. It only makes him look like Ahmadinejad.