You can always blacklist a package (such as linux) in /etc/pacman.conf to avoid upgrading it during pacman -Syu, for example. I had to do this during a power regression in the kernel. However this isn't a long term arch strategy. Note also that arch has LTS kernels, should you prefer.
Not updating a package is the best way preventing security flaws to get fixed
If not upgrading the kernel every week or two is a security hole, most people are pretty screwed. I personally do not like to restart that often. Turning off automatic updates just gives you control of when to upgrade.
If upgrading is not for you, ArchLinux is not for you. You should run a full pacman -Syyu at least once a week and clean up .pacsave files at least once a month. Probably even more often if you are on testing.