How did they hold back? They have already said they weren't done when the game went gold. They have been working on them after the game was sent out to be published and produced. To include them in the original copy they would have to hold the game up. Or they could have just took the month off and not done anything to make the game better. Remember, it is your option to buy and it doesn't change the important aspects of the game.
Perhaps. Perhaps not. Either way it horse armour all over again to me.