Yep. There's no way it can be a diagnostic artifact. At best, it could be one of the many "interesting possibilities" found over the years.
Agree. However some questions to ponder.
1. Was there any linoleum or Formica on the Electra?
2. If yes, could it be determined the type/color used? Does any similar material still exist from the manufacturer?
3. If yes, could one do a chemical/materials analysis to determine similarity?
Even if you could and it was a match that does not mean it was definitive. Still, if Ballard was only focused on aluminum and the engines did he miss any other items?