Here's a story he tells that I enjoyed. He proposed that he teach an introductory course--an altnerative to Harvard's famous EC 10--in which he would both present mainstream economics and several critiques of it. The economics department voted it down by 30-something to 2. One of the senior faculty members told him that there were only two types of economics: good economics and bad economics and that at Harvard they taught only the good kind. He asked the only other econ faculty member who voted for it why he did and Marglin reports that the faculty member said that if any senior faculty member was stupid enough to want to teach Principles he should be allowed to.
The end of the story? Harvard's core curriculum committee unanimously approved the course. So he has been teaching it for some time.