Once logged in, everyone is in there.
I can't think what I may have done or what permission it might be tied to.
I've tried disabling all add ons in config.php and it still occurs.
I have a small template mod to remove yourself from the newsfeed, but disabling that seems to have no effect.
I'm not sure what else to troubleshoot.
I'm guessing it might be a rogue permission, but I can't figure out how a permission affecting one user account relates to guest viewing permissions.