Pacification does no such thing. The Pacification debuff is a short "silence" of sorts that prevents the use of skills (with a few exceptions, mainly large abilities hard-scripted into boss encounters when they change phases) on its own diminishing returns timer. It has no aggro reset properties of any sort, so if a tank is losing hate on a mob by using Shield Swipe it is simply due to using it before having a solid hold on the target.