Presumably to demonstrate that it works on Mac ARM platforms, in response to the question about that.

If was satisfied with my own presumption I wouldn't have asked ;)

That Python app is a popular demo for Cosmopolitan. It's what I would have chosen for that demo, too! It's handy because it outputs a little bit of information about the current architecture on the first line when you start the shell.

There's some interesting background on it in this issue: https://github.com/jart/cosmopolitan/issues/141