And we now see a true side of Luna. The dark nightmare moon that has never gone away and simply tricked everyone into believing that she was gone. After all, you can't remove the darkness from those who don't want it gone. And Luna most certainly never wanted it gone and still harbors hatred towards her sister.
Already did. In ether way she's still no different. She's done it once and if her brainwashed kidnapped children's descendants are any indication, she is more then likely to do it again. It's easier to ask for forgiveness then a permission after all.