Practical effect of foul SHOULD carry the day. This is the sort of hypertechnical application of rules that drives me nuts. Player 4 reacted in a split second and had NO FKN TIME to assess the situation. In "normal" play, perhaps he would have simply been saving P3's ball and called P3 back to finish. The TD having correctly determined that the ball should be drained, any SANE application of rules would not penalize P4. No harm, no foul.