Mint wouldn’t be my first choice, I’ve had nothing but trouble with it not properly mounting NFS shares and systemd scripts not working properly. I’ve had much better results with Ubuntu.
He mentions Fedora as being a free version of Redhat, two other options are available and those are CentOS and Scientific Linux. These tend to be less current than Fedora but more stable.
Also the author makes the statement that the Linux updater updates everything on your system. The Linux updater only updates programs installed with the Linux install tools, such as apt on debian based systems, yum on Redhat systems, zypper on Suse, or dnf on Fedora. Programs which you install from source or download from a website are not updated by the system updater. Also modern Linux can require reboots for some non-kernel updates, particularly libc updates.