To be honest with you, that teacher sounds like a real tool. All that that can possibly achieve is to breed various subtle forms of animosity, either among classmates or towards engineers or towards the teacher or the course.
I can see this being a joke. Entire subfields of mathematics have been built on the assumption that Riemann hypothesis is true. He probably assumed that everyone in the audience would know this, which is not unreasonable.
But it is not an important skill for persuading people, or for cheering people up.