That doesn't sound like a very dangerous mod
I have the script set up on my Lion desktop system, and it causes no problems as far as I can tell. It's configured as a Folder action watching the appropriate Steam folder. Whenever Steam delivers a new or updated mod, it installs it with zero user interaction.
I have Firefox, and it runs fine, though I use Safari as my primary browser. However, I have no idea how stable (or otherwise) Aurora is, and I don't have it, or a Firefox profile.
I have also run the script manually on my Mavericks laptop, and, again, it shows no signs of issues with standard Firefox. I honestly can't see how there could be any interaction. Which version of OS X are you running?
I'm currently working on making a single-click Applescripted installer that will set this script up as a Folder Action to watch the relevant Steam folder. This is already working on my old Lion system, and I now need to create a "signed" version of it so that it will work under Gatekeeper. I'll then test it on my Mavericks laptop, and all being well, I'll post it here for others to test.