While reasonable people can object to the cancellation of Tutu's speech at the University of St. Thomas, and discuss the factors at play in the university's decision, it is quite pernicious to infer that the Jewish lobby conspires to "...stifle an honest debate about U.S. policy relating to Israel," resulting in the continuing "spiral of violence" in the region.
To the degree that the Jewish community played any role at all in the cancellation, they (much like the rest of the organized Jewish community) didn't threaten, intimidate, or coerce, but rather civilly expressed their concerns about Tutu's past statements—the merits of which the university was free to weigh and ultimately accept or reject.
The Tutu quotes that concern many within the Jewish community are as follows: "Israel is like Hitler and apartheid." He has also said Israel "...reminded me so much of what happened to us black people in South Africa..." and, "People are scared in the U.S. to say wrong is wrong because the Jewish lobby is powerful—very powerful."
Quite frankly, many of us within the Jewish community—who represent less than 2 percent of the U.S. population—are alarmed that the mainstream media has begun to come frighteningly close to advancing the historical canard that Jews exercise a dangerous degree of influence in nations where they reside—a myth that has resulted in discrimination, pogroms, and mass murder for centuries.