This is what the Aeon maintainer said about root vs rootless in MicoOS:

1. Since MicroOS is immutable and not meant to be changed then there’s no problem running everything as root; root can’t even write to the immutable parts of the OS
2. The main benefits for Podman on MicroOS are very many while not including rootless. No daemon to crash and make containers unmanageable. Nicer dependency chain making it easier to keep up to date on TW. Support for kubes… and many more

Source thread (Reddit)