What do you mean by "out of date"... what is out of date? According to what?

Livepatch is only for kernel security fixes... it doesn't upgrade the regular packages on your system if that's what you mean by "out of date". You either need to run apt (or a GUI version) manually or set it to automatically update your system packages.

Livepatch is implemented in a hacking way. It dynamically patch kernel code in memory so it should only be used in the machine can't be reboot completely. For a normal machine, use unattended-upgrades instead.

Ubuntu would not be my first choice.

If he can get most of his programs via Flatpak or AppImage, and he doesn't intend to do a lot of tinkering via command line, check out Aurora. The Fedora Atomic distros and the UBlue derivatives are great "set it and forget it" options, and I believe Aurora has automatic updates set up out of the box.

The best part is that if something gets fucked up by an update, you can just rollback to a previous state in GRUB.

Using distrobox, he could even set up an Ubuntu container to install anything that's only available in the Ubuntu repos (and I recommend the companion app Box Buddy).

The one downside is that any tinkering will require learning a new paradigm, since most of the system is immutable, except for /etc and /var, which is where the user's /home directory is (i.e. /var/home).

If all of that sounds too daunting, or you want a more traditional distro experience, install Mint and call it a day. Good luck!