Well, at universities people are very intellectual. The right wing has had a decidedly anti-intellectual stance for quite some time now.
There is a danger of groupthink that anyone who doesn't follow the du-jour trends of college life must be an anti-intellectual. Young people should be aware of this as they leave college and enter the real world. Few things are as insufferable as a young person who plasters their political views into a workplace without respect for the people they work with.
But yes, Milton Friedman would be an excellent commencement speaker. I'm sure there are more great academic conservatives who would be equally good, but very few of them are well-known enough to be considered even if the students wanted a conservative.