This is a terrible idea. I can't wait to see the uproar if this passes and a team loses a game because of this. The debate over the Washington-BYU game last year will be nothing compared to this.
A player taunting someone else while going into the endzone does not have any bearing on the play's outcome. If a player holds or jumps offsides during a touchdown, then yes, that play should come back and a penalty assessed from the line of scrimmage or the spot of the foul. But the player still would have scored a touchdown if he was high-stepping, doing a backflip or soulja-boying into the endzone. This puts too much power into the referee's hands and they are already trigger-happy with throwing celebration flags (see Washington-BYU).
It will be a huge mistake if this rule change passes. Make the kid sit out a play or fine the coach, but don't effect the outcome of a game because a player got a little too excited.