Airbag light repair scam at Dealership?

[1990BlackLS]

Dating a woman with a Lexus she bought used out of D.C., brought back to Michigan as it was rust free albeit high miles.

Passenger airbag light on and they said it would be a simple fix at a Lexus or Toyota Dealer when she got back home.

Take it to Lexus Dealer and they scoff and say, "just trade it in on a new car, why waste your and our time."

She says, "it is the same year, model and color of the John Wick movie car, I love that movie.

Takes it to Toyota Dealer and they say no problem, $200 and we can reset it and you will be on your way.

She starts car after they drop it off in front and the passenger airbag light stays off for exactly three seconds now and then lights back up.

Service writer says, if you leave it overnight we can sort out what is wrong and fix it for you, just sign this work order.

She is talented with cars, did the timing belt herself from YouTube and changed the filter on the AT, knowing NOT to flush the fluid, instead only add to top it off.

Smelled a rat and backed off and now has to have passengers sit in the back until this is sorted out.

Before Toyota Dealer work, light was on as soon as car started.  Now it comes on three seconds after it is started.

Did they get the passenger seat calibration near but not close enough with their equipment and need to "borrow" the car to their Lexus Dealer buddies to get it right?

Told her she is right to stop and take a breath and let me see what the experts say and if they have a guru to recommend for her "movie" car.  She also has the Lexus from the 50 cars list from Gone in 60 Seconds, but that was acid attacked by a passing car.  Michigan hates foreign car drivers with a passion, she garages everything now, nothing visible from the street in her very wealthy white area (Eminem lives just over the hill from her).

[Lexus Owners Club]

I think she was right to be cautious and not proceed with an open checkbook as this could lead to huge repair bills.
It is either going to be one of a few things, although easily fixed!

1. Passenger occupancy sensor - which indicates someone is sat in the seat and the airbag is then active, no one there and it deactivates the passenger airbag.
If a bag or something heavy is left on the seat then this can activate it.
If the sensor is faulty (assuming it has one fitted) then this can trigger the fault.

2. Pre-Tensioner - connection under the seat sometimes goes bad, need to disconnect, clean terminals and reconnect (sometimes works to twist the wire a couple of turns so that when reconnected it has a slight bias onto the terminals and cures the fault)

3. Faulty Airbag or wiring - requires replacement and then should resolve issue.

NOTE:  proceed with extreme caution when working on an SRS electrics. 
Ensure the battery is first disconnected and left for at least half and hour so the capacitors can discharge any residual power then it is safe to work on the electrics or associated components.
Also, do not apply any power to the system when it is down, e.g. multimeter resistance checks as this can trigger an airbag.

When you are happy that everything is fine then reconnect the battery and as soon as the ignition is on it will check the resistance of all components and if correct the lamp will extinguish almost immediately and stay out. It should not need any reprogramming to the car as it is self evaluating after every ignition restart