Note that only the GUI part is broken (mostly due to jailfish stuff); the service itself still works (in defender, the actual engine is separate from the GUI).
So you can manually edit / restore from backup the file .config/harbour-defender/defender.conf (warning, it will be overwritten on defender GUI’s start up).
Then touch ~/.config/harbour-defender/update to use the .path automatic trigger (this in turn will automatically call devel-su systemctl status harbour-defender.service for you).
Android will disable ads immediately if it has already been restarted after defender’s installation (so its /etc/hosts is mapped to Sailfish’ file).
Sailfish Browser will disable ads next time it is fully restarted (warning, the pre-cache might still have an older copy of /etc/hosts in cache ; you might want to kill any pre-cached instance, or restart the Silica UI or reboot the whole phone)