The guy’s a college professor. He should be capable of self-educating on a topic within the general scope of his training and teaching the class. But his honesty does earn him some points. There are plenty of tenured “educators” teaching things about which they are clueless...
I once knew a man who was teaching history at a four-year college. Earlier in his career he had been teaching at a junior college. One spring an administrator called him in and asked him to teach a physics course that fall. He protested that he knew nothing about physics. The administrator responded with, “But you have all summer to learn it.”