IMHO, fouls that can occur after the ball becomes dead are only of the personal foul and USC nature. The WHEN of the WHO-WHAT-WHEN-WHERE of penalty enforcement becomes very important in this. If there is a flag for holding, block in the back, inc face mask, and the like occurred AFTER the touchdown was scored the flag would be disregarded (#13). If FM was deemed to be of the PF nature on A, B could ask for enforcement on either the PAT or kickoff. IF the foul had occurred in the end zone by A BEFORE the touchdown, the goal line would become the basic spot.