Think of the manufacturing engineers that had to think up the design of a miles long continually moving assembly line. Things like being able to pull something off the line, put it back on, designate the points along the line where it could happen, find the space in the building to do it in a small foot print, all the while not screwing up the series delivery of all the different sub assemlblies at all the different installation points along the way for all of the cars being built that day.
This particular event took place right at the end of the line, so there wouldn't have been much coordination needed as it related to the repair as all the scheduled parts would all be on the tub at this point, and it hadn't been "logged" into Chevrolets side so none of the remaining parts would have been scheduled until after the VIN and prodcution sequence number was assigned.
Say a seat had a big tear in it, and had to be replaced, and that was why it got rejected. Where would they get the new one from and what would happen to the one that had to come out of the car?