> I am guessing that means there is no need of a service startup/shutdown
It just means Drew doesn't want to have to maintain it upstream.
(similar to the rationale for not including a .desktop file: it's not necessary).
It would make more sense to have this type of file in the package repository of a systemd-using distribution.
e.g. This AUR already has a gmnisrv.service file: https://aur.archlinux.org/packages/gmnisrv-git/