And a little advice to Valve, next time have developers familiar with Linux working on your Linux client. That
A competent Windows developer would probably just write:
if exist "%STEAMROOT%" rmdir
no dangerous glob needed.
It kind of floors me that they aren't doing some kind of check that the directory tree they are about to delete actually looks like a Steam install before deleting it. e.g. check that ClientRegistry.blob file or SteamApps directory exists under $STEAMHOME.