Multiple sources have confirmed to the Pro Wrestling Torch that there is legitimate tension between Dwayne "The Rock" Johnson and John Cena, which reflects in their war of words. Furthermore, Vince McMahon is doing nothing to stop it as he and those in upper management love the conflict.
As in the past, McMahon enjoys seeing top stars challenge other. He feels the audience will sense real friction between two wrestlers, thus furthering interest in the match he's trying to sell. In the case of Johnson and Cena, the top circle likes that fans are sensing their friction and believing that they may legitimately come to blows at WrestleMania XXVIII.