Protects incest predators?

According to this AP article the U.S. Senate has re-opened debate on a bill to make it a federal crime to transport a minor across state lines to avoid a state's parental involvement law.

Barbara Boxer is leading the opposition to this bill and doing her best to make me believe she got her last name from her former profession and during her past career took too many punches to the head. Boxer opposes the bill because "(i)nstead of doing something to improve the health of women and girls, the Republican leadership is spending precious time on a bill that protects incest predators, throws grandmothers in jail and violates our Constitution."

How on earth does a bill which prevents people from taking minors across state lines for abortions protect incest predators? I'm trying to come up with scenarios and it's just not working.

If a father rapes his daughter, how does this legislation protect him? Is taking a minor across state lines for an abortion something that harms a father who commits incest? It seems that action would help keep the incestous relationship secret.

It seems obvious the legislation would actually help young women who might be transported across state lines by an incestous brother, uncle, grandfather or other relative for an abortion. The last thing an incestous brother, uncle, or grandfather wants the parents of his victim to know is that his victim is pregnant. Forcing their victim to have an abortion without the knowledge of the parents would be a sure-fire way for them to continue their heinous actions.

I'm also wondering how Boxer thinks this bill is unconstitutional considering the U.S. Supreme Court has ruled that parental involvement laws are constitutional.