Nice to be posting on this site, where people don’t immediately buy the party line (and tell me how wonderful air bags are).
And if they did trigger on my car, and I could fix the damage myself, then no way would the air bags be replaced. From what I remember, you just need a resistor in the circuit to trick the computer (and big brother, if you have safety inspections).
As to stability...good question. Obviously cars are not the most benign environment in which to store pyrotechnics.
They seem to have mastered it in the middle east. ;)