I don't know if it's true but it would make sense. If half the margin of victory were fraudulent, then the fraud could have affected the outcome. Not that it DID, but that it could have.
That should be enough to call bullsnit.
I don't think that's the case, in this situation. It would be in a case where the ballots could be cast for either candidate (i.e., the ballot is valid, but we don't know which way it should go); but in this case, the ballots don't belong in the pile, at all. The invalid ones get subtracted from one side, but not added to the other.