I did a fair bit of set work in college, but it took me about a minute to dig some of that up to read and understand the relationship that's being described. I don't think I've worked with sets using actual mathematical notation in over 10 years. It wouldn't have surprised me if I couldn't read it (although I would've found it somewhat distressing).

The weird part is his audience: active students and researchers within the field of CS. They're the ones that I would've expected to be most likely to understand what it said.