For some reason, my dad can rename the protected folders inside of his Mac OS X home folder?

My dad accidentally managed to rename his Library folder, which caused most of his applications to briefly freak-the-fuck-out.

When he realised what had happened, he tried to change the name back, but OS X had already created a hidden replacement. I walked him through enabling and using the root account to delete the new folder, and to rename the old folder back. He logged back into his account, and thankfully* everything was back to normal.

* I didn’t feel like spending 11 hours on the phone

For some reason though, he is fully able to rename or delete the should-be-protected folders inside of his home folder. On any normal Mac, if you try to tamper with the Desktop, Documents, Downloads, Library, Movies, Music, Pictures, Public or Sites folders, you’ll be told that OS X needs them and that you’re a very naughty boy.

Is there a conf setting that stops these folders from being protected by OS X? I can’t find anything on the Google.

He’s using Leopard.