

Whether you like it or not, that’s more or less what happens. You can/will lose a bunch of accounts for causing trouble. Sometimes I think it’s a bit over the top. Instead of keeping out toxic or non-contributing folks it becomes a personal vendetta or innocent violation.
Overall, I’m a fan of banning known bad users, but restraint should be used and collected personal information should be minimized.
I think that error is related to a missing dbus session but don’t quote me on that.
You will probably find it easier to use a system level service, but run it as your unprivileged user with User= and Group= directives. Once you get that working, there are various other parameters you can add to harden the service if you like.
This is a good reference for hardening: https://docs.arbitrary.ch/security/systemd.html
The arch wiki has a good general reference for all things systemd: https://wiki.archlinux.org/title/Systemd