It seems as if the two functions SetInputWorldGeometry3D and GetInputWorldGeometry3D are not used anywhere in the source code. For me it looks like all relevant code uses the two functions SetInputWorldTimeGeometry and GetInputWorldTimeGeometry instead.
Inside of the SliceNavigationController I also couldn't find any useful usage of the variable m_InputWorldGeometry3D. Everything seems to be covered by the m_InputWorldTimeGeometry variable.