Tab on user page doesnt show up
You don't define the 'page callback' for the MENU_DEFAULT_LOCAL_TASK since it is taken care of by the 'root' page, plus without any additional tabs it won't show up anyway.  If you add another MENU_LOCAL_TASK it should show up.  You can think of the default local task as the page itself, there would be no reason for a VIEW tab there without anything else like EDIT UNPUBLISH etc.