The St. Thomas statement on Bishop Tutu

I appreciate the chance to read, and think about, the letter of the St. Thomas faculty regarding the Bishop Tutu situation.  To be clear, I'm a big fan of free speech.  But, I wonder, is this really true?:

To reject a distinguished speaker based on worries that his words may cause hurt or offense to some is entirely at odds with the search for truth that should characterize a Catholic university.  Speech taking positions on controversial subjects will often be offensive or hurtful to some people.  Nevertheless, a Catholic university should be willing to open itself to such speech – and criticisms of that speech – in order to learn the truth.

I would not have thought that "the search for truth that should characterize a Catholic university" requires such a university to give a platform to all speakers, no matter how offensive their views or statements.  Somewhere, I assume, there is a line.  Ex Corde, I would have thought, is not a mere baptism of John Stuart Mill. 

Yes, the worry that statements-in-pursuit-of-truth might offend or hurt should not be enough -- at any university -- to trigger the exclusion of an otherwise worthy speaker.  But, I assume that my friends who signed this letter do believe that the "search for truth / marketplace-of-ideas" argument is not always trumps, and so it seems that, underlying the letter, is the implicit claim that Tutu's "comments on the Israeli-Palestinian comment" are not, objectively, offensive (and offensively false) enough to warrant his exclusion.  Am I right about this?  If someone believed that Tutu's suggestion of an instructive comparison between the Holocaust and Israel's efforts -- which may, of course, be criticized -- to defend herself from terrorists calling for her to be "wiped off the map" is horribly misguided, what guidance would my friends at St. Thomas offer about how that person should decide, as a general matter, how offensive is too offensive?

Also -- and I intend this as a serious, good-faith question:  Given Tutu's regrettable failure to understand well, and speak clearly about, the immorality of abortion, do those who signed the statement think that a Catholic university that welcomed Tutu to speak about peace-making should -- given the celebrity, and near-saint, status he enjoys, particularly with students -- do something (anything?) to identify his unfortunate blind-spot on abortion?  To challenge him?  Should a Catholic university that welcomes (and celebrates, and honors) Tutu have any duty to use his presence as a kind of teaching moment?  (As, for example, Pres. Bollinger did at Columbia.)  To be clear:  I'm not sure what I think about this -- again, I'm all for the rough-and-tumble of free speech -- but I'd appreciate others' thoughts.