After writing this, I realized that the Hindenburg part is actually only worth 2 points when unfinished, so 13 points is correct. I guess I was trying to make the situation agree with the poster's comment that the "last 3-point-airship made the difference". But after looking more closely at the situation, I see that he probably meant if the German player had taken that card, then the score would have been tied and the German player could have won via the tiebreak conditions.
