Thanks for the thoughts, Justin. I'm still trying to think through this, so for the sake of exploring how the argumentation might go, I would probably say that it's not any more unfair since aff isn't taking away any negative ground. So basically, as long as the negative can argue everything they should be able to argue (topical counterplans obviously excluded from a res-centrism perspective), it's not unfair. And they can, because the aff isn't advocating any part of the SQ. Does that make sense?
You might do some research on defenses for conditional affirmatives--basically the same thing as AJAC. Actually, I've never even heard the term AJAC outside the NCFCA. They're not uncommon in other leagues, though, so you might do some quick googling before you reinvent the wheel.
Conditional affs, even when defended from the res-centric viewpoint, don't necessarily preclude counterplans. The neg can still claim parametrics, they just have to say the res became two different points (plans) within the resolution, as opposed to the more common one point. To use the old analogy, if the entire res is a big circle, a single aff plan is one small circle inside that. The rest of the big circle becomes neg ground. An AJAC is just two small circles.