It was spelled out that Sue wasn't against the Laws of Magic as she wasn't Human. I guess her instance was a form of Grey Necromancy perhaps, at least not Black. Actually, he did try to control her at first vs he didn't try to control the ghosts in Grave Peril. So that may figure into the equation too but still it wasn't a Black act.
So, the method of the Necromancy is part of the determination of what is Black, or White, or Grey. And the Method considers what type of entity is used, and what level of control is given to the entity raised. I'd think if Harry had taken the Spirits in GP but bound them to his will against their will I'd say that would cross the line into a more Black magic than White.