Biped weighing 4000 kg grabs sauropod by head. A shake of the head, and biped is flung into the woods? I am skeptical. In other words, I think the well-placed crushing bite was _perfect_ for killing long-necks.
Reductio ad absurdem: if your body is as big and as mobile as Mount Shasta, and your neck is as big as a pencil, are you a 'huge' opponent?
Yes. When you weigh 20 to 40 tons and are moving, that's a BIG yes.