Mostly because the dev linked to the Homebrew installer when announcing(?) it on her Twitter account[0], but also because the forked repo[1] that contains the patches just shows the original README.

This isn’t an official port to the M1 — it’s a custom version patched by a different dev.

[0]: https://twitter.com/simnalamburt/status/1434244533001224192

[1]: https://github.com/simnalamburt/podman