His top students were capable of entirely understanding Scheme within a day or so (but not capable of entirely understanding all of Python and all of PyPI). He wanted students to be even better than that. He wanted them to lead productive and resilient collaborations even when they didn't or couldn't entirely understand the small parts.
Given a day, top students can understand enough of Python to write enough code to get the point about how programs rely on abstraction and composition.
(Of course, the latter part of the course, describing the implementation of the runtime, would need considerable rethinking.)
