If you were concerned about safety, you wouldn't be buying a Miata. Not that the Miata isn't well built, but it's a small, two seat, convertible on a road system dominated by SUVs, Minivans and trucks. If there is a collision, the Miata is going to lose.
You might want to try to find out which airbag is causing trouble. If any passengers are likely to be small framed -- children or shorter women, you might want the passenger side first generation airbag disabled anyway. Same for the driver side airbag if you are small framed. You'll have to read up on airbags and make your own decision.
If your state has safety inspections, you probably want to know what you are going to do about that flashing light before you go off to get an inspection.