Eddie seems a little weird about his speakers and cabs... I recall from the original 5150 combo the whole spec that the combo is exactly half the 4x12 and 120 watt head. So 2x12 and 60 watts. However, even then much was made of the fact that the speaker section was supposedly exactly half the volume/size of the 4x12.
The same is what they're doing here... the 2x12 (60 watts) being exactly half, supposedly volume/size as well, then 1x12 being exactly half of the 2x12 again... I see the logic.. not sure if I agree on whether it's ideal or not, but it's his company so...