Another tell that the sheath was completed by Clarence Moore is the fact of the edging done around the edges of the sheath. Heiser left the top of the of the sheath flat so you can see the tooling around the edge left by the foot of the machine.
This photo illustrates a Heiser sheath with a flat/tooled edge which is how they did their sheaths. Also note the absence of a rivet securing the horizontal keeper. The sheath featured in this thread has a rivet securing the keeper, as Moore did. Not sure if Moore secured ALL of his horizontal keepers with rivets. Perhaps Joe has knowledge of that.