So if the failed setup.command is to blame, how would one go about removing (or undoing) the setup
There's no real need to undo the setup, as it's just creating a single directory that other traditional unix applications (e.g. kermit, IIRC) may conceivably use. If you're trying to "remove and reinstall", don't bother - just run the stup again.
Our new iMac will be here soon, so this computer could be reformatted (and is a bit over due for a proper cleaning), but it might help other users to know how to uninstall on os x.
Like most OS X apps, just delete the application from /Applications and that's good enough.
-j