While it’s true that both python and js are interpreted languages, making them highly portable, JS at that time was a very lightweight language with a robust runtime offered by mozjs, that was built to be easy to embed into other systems, while python was designed for being the framework in which you build apps directly, hence requiring deeper dependencies.
Sources:
https://blog.fishsoup.net/2008/10/22/implementing-the-next-gnome-shell/#comment-1691
https://blogs.gnome.org/alexl/2008/09/09/embeddable-languages-an-implementation/
https://www.reddit.com/r/gnome/comments/120edc0/comment/jdgwyoq/
Depending on how you define all powerful God, Fallout New Vegas