It's a play that needs to be discussed for rules clarifications, as teams are beginning to use it with more frequency.
Google "fake kneel football" and you can find a number of these plays occurring recently.
However, lots of time when a team lines up in victory formation, the officials will tell the defense to not rush (obviously for safety and to temper any flare ups). If that is happening before the offense performs the fakeout, then the defense has a legitimate appeal.
Read about the Purdue-Arizona bowl game from a couple of years ago. Arizona defense claims that they were told not to rush by the officials. Purdue runs a fake and gains big yardage to set them up for the game-winning field goal.
For now, the play is legal. But if it continues to be used, I can see a need to clarify its legality. Similar to what happened with the "wrong ball" trick play.