[tor-relays] experiences with debian tor 0.2.8.6 package from deb.torproject.org

[tor relay]

> So there is no way to disable the default instance using systemctl after all?

To answer my own question:
systemctl mask tor at default
disables the default instance for real.

..but I'm still curious why tor at default is a static unit (without [Install] section)
https://bbs.archlinux.org/viewtopic.php?id=147964