These whole issues would disappear if hotels would use half a brain to figure out what prices to post in the reservations system.

I recall working for a major luxury hotel chain that had $0 rates all over the place, yet our reservations provider gave me idiotic excuses about why the $0 rates existed and refused to remove them. Of course we never honored them, but nor were the powers that be at all concerned about them.

I have no idea about whether Hilton should honor the rates, but maybe they should think about automated controls that prevent confirmation numbers being generated for reservations made at $0, without a manual override.