Is it possible to deselect element but keep it active? In this question I found out uses for being able to deselect the active object. 

You can basically use the active-but-unselected object as a transform pivot point for the rest of the object selection without affecting the active object. Which is great.

You click-select the object to make it active, then border-deselect it. It's now unselected but remains active. 



But here you can see the behavior is different in in Edit Mode. 



While this doesn't seem like a big deal with a vertex selection it would be nice with an Edge or Face to modify around a face's pivot point without actually modifying the active face.

I've been able to force deselect an active element through python but I was wondering if there was a way without scripting.
Based on the comments it seems like the answer to the question is that Active-But-Unselected elements in Edit Mode are not really intended to be used the same way as Active-But-Unselected objects in Object Mode.

Active verts and edges become deactivated when unselected, and unselected faces, while remaining active, become hidden which kind of forces you to "work in the dark".

For the specific use-case I posted in the original question it seems like the cleanest way to achieve that is to use the 3Dcursor as the pivot like sambler and user3800527 mentioned. 

To keep conventions consistent across modes in Blender I wish all elements had a persisting active item that remained visible regardless of selection. It would make learning Blender a lot easier without having to ask so many questions :)