If you’re writing the script to be used by multiple people, or on multiple systems, or for CI runners, or in containers, etc. then there’s no guarantee of having Python (mostly for the container situation, but still), much less of its version. It’s far too easy to accidentally use a feature or syntax that you took for granted, because who would still be using 3.7 today, anyway? I say this from painful recent experience.

Plus, for any script that’s going to be fetching or posting anything over a network, the LLM will almost certainly want to include requests, so now you either have to deal with dependencies, or make it use urllib.

In contrast, there’s an extremely high likelihood of the environment having a POSIX-compatible interpreter, so as long as you don’t use bash-isms (or zsh-isms, etc.), the script will probably work. For network access, the odds of it having curl are also quite high, moreso (especially in containers) than Python.

If you're distributing the script to other people then the benifit of using python and getting stuff like high quality argument parsing for free.