You have a tiny systemd library which does little more than checking if systemd is running. It's a helper library for doing that check. Within Devuan they didn't want this dependency, but that's unrelated from being able to use software under another init system.

There's a huge difference between not accepting any dependency with systemd in the name vs being able to use another init system.

That some software has a dependency does NOT mean that the software is restricted to only run under systemd.