ABB reveals grandchildren hidden from public

I submit this as a bug by comparing to the core Book Nav.

I really need to be able to reorder Book menu, and I thought ABB was the ticket. Unfortunately ABB shows grandchild nodes those which are hidden from public and/or hidden from other OG groups. The original Book Nav Block does show expandable menu but it doesn't expand if you are not logged into the specified OG, which was a better behavior for my needs.

The best solution for me is that Book Nav block even doesn't show the expandable indicator if not logged in. Is it possible?