Apparently your son's "adviser" has confused seat belts with airbags.
Apparently not.
Many late model vehicles have seat belt tensioners that retract the belt in the event of a collision. All that I have personally seen were round cylinders about 4" long and about 3/4" diameter and they do have an explosion to retract the belt (probably about 2"-3" travel). But it's all contained it the cylinder. The ones that I'm aware of are all contained in the latch side of the belt (buckle section w/button) which would be to the right of the driver and would not effect normal operation of the regular belt retractor which is on the left of the driver.
If the belt tensioner is deployed in a collision it will turn on the air bag warning lamp, same as air bag deployed or malfunction. The lamp will remain on until repairs are made, it can not be just turned off with a scan tool or whatever. If the air bag light is not on this suggest the problem is the regular belt retractor on the left of the driver.
Every vehicle determined to be a total loss by an insurance company is sold at auction. 99.9 percent of them are bought by re builders. The re builder is not concerned with customer satisfaction and apparently not the federal government. If the seat belt tensioner is deployed it's a simple fix to install a 29 cent resistor in the circuit. It satisfies the air bag monitor and keeps the lamp out. There are lots of quality re builders out there but I think they are out numbered by the shysters. Even if your lamp is out it doesn't prove the retractor is OK.
Manny vehicles have a switch located in the door, most are located in the B pillar that urges the belt to rewind when the door is opened. Open the door and slam shut several times
Remove the upholstery from the seat and have a look. It's not very hard to do on most late models. I can't speak for the Dodge but on a Ford at the bottom of the seat back the upholstery is fastened together like a "zip lock bag" just pull it apart and then roll the upholstery inside out, up the seat back.
If you determine the (left) retractor is malfunctioning I would suggest you don't try to repair it. It's assembled like a swiss watch and the outer parts are plastic and must be broken to get inside. It can be done
but it's a federal offense.
Have a few beers and call me in the a-a-a when the snow melts off.