doesnt prove anything... the seven swordsmen have their very own cards, yet they arent playable.
Proves he's in the game
We already had proof that he was in the game from the achievements list. Whether he is playable or not is the question. By all means he SHOULD be playable. But it wouldn't surprise me if they didn't just to have the selling point of "play as Madara!" For Storm 4 or Generations 2. More money for CC2!