Note that 3. Ga8-f1=Q is not a valid defence for black, since it allows wGh1 to travel to the right, across the entire 8th rank, returning on a1 and using bQd1 as a hurdle to attack bK.
Note that 3. Ga8-f1=Q is not a valid defence for black, since it allows wGh1 to travel to the right, across the entire 8th rank, returning on a1 and using bQd1 as a hurdle to attack bK.