Front Air Bag Sensor Control problems of the 1997 Nissan Maxima

While driving our vehicle on the interstate, my son rear-ended a Ford winstar van. He believes that he was going approximately 60 mph and was able to brake to some extent before hitting her rear bumper. Fortunately no one was injured. However there was extensive damage to the front of the Maxima. This included the front bumper, grill, radiator, hood and other components that I was unable to assess. However our body shop and insurance company felt that the cost of repairs exceeded the value of the vehichle such that they "totaled" the car. My concern was that with such extensive front-end damage the air bags did not deploy. Nissan seems to think that this was appropriate. How can we determine if this is correct. Please advise. Thank you.