Penalty in the end zone

[mikesears]

From the NFHS website (Rule Interpretations section):

SITUATION 18: B1 intercepts a forward pass in his end zone and attempts to advance. While in the end zone, A1 tackles him by the facemask and B1 fumbles. The ball bounces forward into the field of play and rolls out of bounds at B's 2-yard line. RULING: If the penalty for A1's facemask foul is declined, a new series is awarded to Team B at the out-of-bounds spot. Since the final result of the play is NOT a touchback, the enforcement spot is B's goal line if the penalty is accepted. First and 10 for Team B on its 15-yard line.


Which one is official? The casebook or the website?