I don't think this is something they should be doing if this is indeed their plan. What about the people that will be genuinely disappointed about this only to find out that it was just a bad joke? Some are going to cancel their pre-order because of this you know. Some are going to say **bleep** it I'm not buying the game. What about those people? Why would they alienate part of their fanbase just to create bad publicity?
Those people will go back and buy the game.
What is the point of this then? It will only create bad publicity when people learn that there are more characters when they were told othewise. And not everyone will buy the game after learning the truth. Some are not hardcore fans and if they believe this rumor, they could easily spend the disposable income they have on something else. When they learn the truth, they may not have enough money saved to buy the game or perhaps their priorities have been shifted because they became alienated.