One of the criteria for killing the play pre-snap was not met here and that is the 3-seconds without any replaced player heading to the sideline. On this play the replaced player is heading out immediately but just didn't have time to reach the sideline. He would have done better running directly off on his own side of the ball.
On another note, watch the snapper closely on the play. He's got his butt up and his head down locating the QB and then starts bringing his head back up, his butt back down, and while still moving into his normal stance quick snaps the ball apparently trying to catch B with 12 on the field. Should this snap have been flagged?