Is it a shock to anyone that universities are mostly filled with "left" leaning folk? These are centers of learning, and it's in most cases a given that new knowledge leads to progressive views. It's not indoctrination, it's what happens when most normal people are shown different perspectives, and often are forced outside their zone of comfort. Outside that zone, givens that were taken for granted are shown to be not so clear cut. While conservative views are by contrast slow to change.
That doesn't mean conservative views are suppressed. Quite the contrary. It does mean that some generalized conservative views will be challenged, and that's what happens at university. I'm exposed to new ideas, many old ideas that built the foundation for new ideas, and I'm challenged to see a larger picture. Some people will keep their idealism, others will soften, or perhaps harden on those new ideas.
The guests at universities tend to draw out: interested students, sympathetic people from the community, and occasionally ideological opposites. I've never been at one where a pie was thrown in the face, but then my schools haven't been the type where one would see Ann Coulter appearing to give a talk.
This canard I find to be a particularly paranoid talking point for conservatives.