don't remove libgfortran.so during customize_airootfs.sh
libgfortran is required to run any numpy-, graphviz- or matplotlib-based program, for example the "dot" visualization tool often used to display dependency graphs, for example from systemd-analyze or for package dependencies.
While dot & co. are not part of SystemRescue, installing them with pacman is easy.
But the removed libgfortran is not recognized by pacman, so running those programs
won't work and the solution (reinstalling the gcc-libs
package) is anything but
obvious to someone without deeper knowledge of SystemRescue or Arch Linux packaging.
Even though the lib is 9 MB unpacked, final iso size just grows by 1 MB, so it can be packed quite well.