Normal administrators seem to be able to edit Super Admins. I looked over the config file, and it seems like there is no "unalterable" user section, so I'm assuming Super Admin is supposed to be uneditable.
I know it seems silly to make someone an administrator if you don't trust them, I do trust my only other administrator, but if they were ever to go on a rampage nothing would stop them from taking over the website .
I agree, you should -never- be able to edit super administrators. Even if you have complete trust in someone, there's always stuff that can happen. (like someone else gaining access to the administrator account)
Actually, being able to protect users from edits would be a nice feature anyway.