When the goal is scored the ball is essentially played over the end line by the scoring team. Posession of the ball is for the defending team, as it would be in the event of a throw in or goal kick. So, the team taking the kick has the responsibility to not delay the game. Actually, the player from the scoring team could be deemed to be causing a delay in the restart by attempting to retrieve the ball. There was guidance given to referees some time ago to be mindful of this and attempt to keep the scoring team from attempting to retreive the ball, just because bad things can happen in this type of situation. So while it may be considered an unspoken rule, there are sufficient rules in place to account for the situation.
According to the rules this is not an issue in high school as the clock is to be stopped after goals are scored.
