He's saying that you academics create a self-reinforcing belief system in which certain opinions are labelled acceptable or unacceptable largely or solely based on credentialism and their adherence to the preconceptions espoused within your bubble. A giant cult, essentially, that filters out ideas or ways of thinking that do not meet with its approval.

Take for example the derisive opinion of certain snooty academics about the work of Graham Hancock, or those millions of people who do not agree with the "global warming" narrative.

You will learn that academics do not have a monopoly on intelligent thought. There are many brilliant people in the world who largely reject that entire system as being obviously broken and corrupt.