Are you serious? The owner simply renewed it. Back then, it was super easy and super cheap to get replacement badges and decals from the suppliers. I still have some envelopes from Fat Chance, GT, Scott and Klein. Klein and/or Merlin even mention replacement decals in their price list sheets for dustributors for super low bucks. literally anyone could simply order them and apply them to their older bikes.
Frame sitting in the factory for 3 years before being built up was the only possible answer you came up with? You wouldnt make a good detective