All depends, really. You cannot simply kill in self defense true. But if you are placed in reasonable fear for your life, then yes you can kill in self defense.
He wasn't simply bigger than her. He was solid muscle, dragging her into a van and basically promising to rape her if nothing else. He approached her, he grabbed her and he threatened her. Three strikes easy.
It's a technicality in it's truest sense but that's the way the law works.