I was thinking this as well.
At Nuremberg, this choice was very deliberate. Several of the convicted Nazis filed appeals requesting to be executed by firing squad rather than by hanging, because they saw it as the "military" way to die, befitting their status as soldiers.
Nuremberg officials refused, insisting on hanging, because they saw these men as criminals, not soldiers, and hanging is an ignominious death reserved for criminals.
A firing squad is too good...he should be hanged...