All gods can get to -1 cards. The turn before, if they were at one card, the following turn it will draw two cards. In reality, it draws one card, but the counter decreases by two. The reason the opponent doesn't deck out in this case is because of the way it is coded. The false god AI draws two cards simultaneously, meaning that there is only one check at the beginning of the turn to see if it has a card to draw. Because there is still one card to draw, the condition for loss by deck out is not met, and it does not lose. The following turn, however, the opponent will deck out, because when the check for card availability is made, it will determine that no cards can be drawn, and you will win by deck out.
The easiest way for this bug to be fixed would be for zanzarino to employ two normal card draws instead of a single double-card draw. This will create two checks for card availability and will allow for deck out when the false god has only one card to draw.