So, banning the anonymous user is by design because it serves a purpose?
No idea why you are arguing.....you know where the bug tracker is, if you feel ti is a bug submit it! The fact the anonymous user does not show in the banned user names when banned is another bug as you can not un-ban it
EDIT: However playing with it shows there is in my opinion actually no bug present as founders can log in still and you can add the Anonymous user to the
"Exclude from banning:
Enable this to exclude the entered users from all current bans."
section which will remove the ban and exclude it from banning again I my playing about was correct
I have submitted it to the bug tracker so the devs can decide
EDIT 2: Fixed in cvs