general problems of the 2005 Buick Rainier

My 16 year old son was making a left hand turn out of a school onto a road with no curve, no hole, no accident but the 4 side air bags deployed for no reason. He was ok and pulled over for safety and got a ride home. We had it towed home and contacted gmac Buick and they had it towed to a dealership and had a diagnostic test ran and found no reason for them to deploy but they said the car had been altered because we had put subs and a radio in it through a lisc. Professional but that makes them not liable for anything that would happen. They said putting a radio in can cause the bags to deploy or brakes to fail and it is in their manual and they are not liable for any problem if we alter the car in any way. If this is the case anyone with an aftermarket radio should be warned that their child car anyone can be killed and it will. E no one's fault. I am out a car because insurance said they don't cover it because it wasn't an accident and gmac says it happens not uncommonly but that they will not help in any way. They told me I was not allowed to talk abijt this to anyone. They read me a statement on the phone which said I can not talk outside of gmac. They don't want people knowing this is happening. People need to be aware that bags can randomly deploy and if he was in the interstate he could have been killed. I am terrified to get in it and drive. Why do people not know this can happen. Why is gmac not doing anything or putting out psas saying people could die if they out sibs in professionally or otherwise.