Well I think we can guess why that would be - after all the controversy surrounding the project at the time, I doubt if anyone had the appetite for leaving anything laying-about. Besides, I guess it depends on what u mean by "complete destruction" - all that happened was that the jigs were dismantled and the wooden mock-up burnt - the partically completed airframes were sold for scrap and the the rest is history. There's nothing suspicious about it really, it's just that so many people have tried to paint it that way.