You could measure the resistance of the airbag with a multi meter then get a resistor with the same valve and wire it into the plug in the steering wheel to trick it into thinking the air bag is there.
Be careful tho WHEN PROBING an air bag as an induced voltage could set it off I don't trust them.
That's how I would go about it but I don't like playing around with SRS systems to much tho and just be aware none of the other air bags and if it has seat belt pretensioners won't work if the SRS system has a fault eg light on and in your case 1 removed
