At least the in the context of what you've posted here, the 'fix' is irrelevant voodoo, ignore it.
Are you using an IDE with a debugger such as Flex/FlashBuilder?
If so, set a breakpoint on this line:
authVO = note.getBody() as AuthVO;
Now run your app in debug mode and navigate to the point that this breakpoint is hit.
Is the note body null? (in the variables view, inspect note and see what's in the body property) If so, there's your problem. The AuthProxy didn't include the AuthVO in the note.
If not, then inspect the contactsControlBar property. Is it null? If so, there's your problem. Can't say why you've fetched aground here with a mediator that doesn't have a live view component yet, but I suspect your startup sequence could have something to do with it, or Flex's deferred instantiation might as well.
If contactsControlBar does exist, do its children authLbl and uNameLbl exist? Again, couldn't say why they wouldn't be there, but you're being to intrusive with the Mediator here anyway.
Encapsulate the implementation of the view component so that changes to it don't require the Mediator to be refactored. You should have a method on ContactsControlBar that accepts an AuthVO like this:
public function setAuthVO( avo:AuthVO ):void
authLbl.text = authVO.getUserRole;
uNameLbl.text = authVO.getUserName;
And inside the Mediator:
contactsControlBar.setAuthVO (AuthVO( note.getBody() );