How will a spanking ban help abused children?

The New American recently reported on a controversial law passed in Delaware, that effectively bans parents from spanking their children in the home. It quoted Biden saying "Far too many children are the victims of abuse, neglect and assault and [this bill] will go a long way to better protect the children of this state".

Not being familiar with Delaware legislation, I studied the laws in question, and what I learnt there left me convinced that this law will not help to protect abused children at all.

The first thing that caught my eye, was the definition of child abuse as given in the bill:
"Abuse" means causing any physical injury to a child through unjustified force as defined  in §468(1)(c) of this title, torture, negligent treatment, sexual abuse, exploitation, maltreatment, mistreatment or any means other than accident."