The Arena drake comparison makes the most sense to me also. However if Blizzards reasoning behind it is they don't want us to blow through earlier content with better gear to obtain novelty items, such as the Amani War Bear change and now this, then to be truly fair they need to remove all mount rewards prior also correct? Goodbye Skadi's mount, Malys, Sarth's, Culling timed runs etc.
Also is the mount from ZG still available? Tiger or Raptor or whatever it was, wouldn't make sense to have removed that along time ago? Who knows what Blizzard thinks half the time with their spur of the moment decisions /shrug