Yes, and that's the problem. The entire federal NSSF lawsuit is based on a question that's already been answered. The allegation the lawsuit is making is "there's no guarantee that someone else won't interpret Maura's edict differently as it applies to Tavors, etc."
Even a best case scenario win for our side in this case merely codifies the post 7/20/16 reality that Maura has laid out, it doesn't bring new AR-15s back to MA.
So... why wouldn't the AG's office just say, "OK, you win"?