It would be extremely difficult and expensive to change the VINs on the vehicles. They are stamped in many places, including the frame.
Ford doesn't want the vehicles sitting, they do not make money on vehicles that are sitting, in fact, they have spent a lot of money making vehicles that are a drain on their resources.
They also have union considerations, if they have parts, I'm sure that the agreement with the UAW requires the plant to operate.
It's most likely poor scheduling and unmet delivery expectations from their suppliers.