If there are certain seats that AF doesn't allocate to "paying" (vs. award ticket) customers, then, when they allow other codeshare airlines to give out seats, it is incumbent upon AF to keep those seats from being used per their reasoning. How the heck is DL supposed to know this if AF hasn't done their work? As far as DL is concerned, a J seat is a J seat unless otherwise notifed. Your real beef is with AF.