Driving is most assuredly not instinctive.
And at 70 MPH, it doesn't matter if you try to protect your baby; that kid's going to be an unguided missile until it his the steering wheel. A 21-pound baby at 70 MPH has a kinetic energy of 2,156 foot-pounds. That energy gets expended independently of the vehicle's kinetic energy in a collision, unless the kid's hard-mounted in place.
The Incredible Hulk couldn't hold the kid securely, using his arms alone, in that kind of situation.
And that deceleration trauma is a b&tch.