Was just reading the block of code regarding gdm3 and autologin. That code is not active, but I think I'll need to account for autologin, in case anyone is using this script with a live distro that has it enabled. Otherwise, the display manager may hang while trying to log in the non-existent user.
Oh, it gets worse...
If console autologin is enabled, the script will die with a usermod error if you're running it from a console in which you used 'su' to get root. Dropping to runlevel 1 gets around this. That's how I dealt with the problem when I wrote an earlier version of this script for debian-live. The other way to fix this is to include the code in the cli refractainstaller, just as it is in the gui version, and make the changes in chroot.