I am a programmer and not a mathematician. I studied more math than typical (almost minored in it) but all of it undergrad and it's been more than a decade sin

I am a programmer and not a mathematician. I studied more math than typical (almost minored in it) but all of it undergrad and it's been more than a decade since I've done anything formally academic. I read some of the comments here before reading the article, and I was expecting something significantly more complicated and esoteric. Set builder notation, element-of, and quantification - it's practically Python. I find myself genuinely shocked that people here are finding it inscrutable, much less those in the audience at the talk. I can't help but wonder whether most of those with their hands down weren't able to understand but lacking confidence that their read was correct?