Could be a number of things, including the ideas you posted. Impossible to tell whether this is a direct result of the accident or something they disconnected while working on the car. Many shops "safe" the SRS system while banging around under the front end to avoid tripping the bags and costing themselves big money. There's also a personnel hazard if someone is in the car.
Either way, the car isn't "fixed". They need to finish the job. Hopefully, its something simple. If not, they'll need a MB compatible scanner to read the system. After the repair, make sure the light comes on for a short time when you start the car (its the system diagnostic checking the system). I've heard of repair guys pulling the bulb.
And, yep, your SRS system is "off line" while the light it on.

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KenP

1996 S500 W140 Coupe