User blog comment:AngelOfLight666/PE Proposal: Zamasu/Goku Black/@comment-27131953-20190705142630/@comment-36757750-20190705143645

The "Pure Heart" thing in Dragon Ball is normally used as a plot device for Goku to be more powerful, even Vegeta who obviously is not pure of heart helped Goku to achieve Super Saiyan God by giving the energy of his "pure heart", which again, he doesn't have. So no, Zamasu only does have the ability of having a "pure heart", because he's a kai, that's it, Aku, for example, is made of evil but is not pure evil because he doesn't understand morality, so no, not a mitigating factor, at all.