Hi,
Basically the admin toolbar (AutoHidePanel) is looking for any WebControls that have the .Visible property set to true. If it finds none it hides itself. The problem with the logoutlink is that it does have a Visible property and it is true even though it won't render itself if the user is not authenticated. I've fixed this in the source code repository so that it will have Visible = false if the user is not authenticated, so it should work in the next release of mojoPortal.
Best,
Joe