At which point of building a car separate parts become a car? And during maintenance (lets say engine replacement) is a car still a car? I'd say it is if meant to be used as a car again.
Right. So, is a stone box in a pyramid chamber that there is no evidence ever held a corpse, or even had a lid, and certainly will not have a corpse in the future, really a sarcophagus? It seems to depend on overconfident assumptions.
Given their experience, a decoy that looks like a looted tomb would just be good planning.