This is Stanford, they aren't teaching the next generation of applied ML practicioners -- they are teaching the next generation of theorists. This is a perfect class for that and getting their students ahead of everyone else. I'm jealous of them.
I've never before paid course numbers too much mind, but it does surprise me there's not yet some widespread standard of to help graduate admissions officers, graduate advisors, and grad students themselves when determining prerequisite eligibilty.