What you suggest is in any case not what Rossi said he did in the paper, nor the whiteboard, nor originally in response to further questioning.
THH, your thinking is narrow and quite constrained. Do you not suppose that Rossi and his team have measured the device in every which way? Why wouldn't they?
Do you really suppose that they have only measured it the way that is shown on the whiteboard? Or perhaps they have measured it only in the way that it is described in the paper. Or maybe they have measured it only in the way that it was described in response to further questioning? LOL.
Or maybe Rossi always simply assumed the resistance of the reactor was zero, and didn't bother to ever actually measure it. LOL.