What you are saying would make sense. I have an issue with a switch inside the seat belt latch with the result being that the airbag light remains on all the time. The seat belt works fine though. It would be incredibly shortsided of VW engineers to totally disable a system such as the airbag system for such a minor fault. Seems to me that the light staying on only indicates that there is an issue to be resolved and not total disabling of such a critical system.
But, as others have asked, do you know for a fact that this is true or is it just your "common sense"?