shell is the only portable language. It works on all Linuces, BSDs, and even on WSL. Anyone with a tiny bit of sysadmin experience knows sh.

Python is far too much overhead for something as simple as firing shell (!!) commands and dumping new files in a tar archive.

And also, shell is extensible in the most simple way: you just write a program name, and boom, it runs.

Shell is simple, stable (remember the debacle of Python 2->3?), safe (no pointers, etc.), readable (compiling can even introduce issues), and dangerous only if you do it seriously wrong[0].

The only remark I have regarding code quality is that the word splitting warning is disabled for the entirety of kiss: I would have disabled it on a per-occurence basis.

[0] https://github.com/valvesoftware/steam-for-linux/issues/3671

PS: the most secure open-source OS out there has a package manager written in perl, with priv-sep (https://github.com/openbsd/src/tree/master/usr.sbin/pkg_add).