Pacification usually works like this: If it can be applied to a Boss, it wont interrupt the skills/important skills or the Pacification debuff will just be resisted.
Also you can only use Shield Swipe after an succesfull Block -> makes it unreliable.

The need for 2 Tanks would be Turn 1,2,4 the new Extreme Modes Garuda, Titan, Ifrit. King Mog could be maybe outgeared, for lower Itemlevel groups most likely 2 Tanks.