Is this obstruction?

[Larry1953]

Little League 10-12. Runner on second, two outs, score 4-3 in favor of our opponent, bottom of the sixth. Batter hits a clean single to left and, coaching third I wave the runner home since a weak hitter was coming up next. Unfortunately, the runner I sent home was your typical chunky catcher and pretty slow afoot. The left fielder made a perfect charging pickup and a great throw to the catcher on the fly about 10 feet up the line. The runner realized he was a dead duck and retreated back to third. The catcher threw a little high to the third baseman who was standing about 10 feet in front of third. He jumped up, the throw deflected off his glove back into LF, came down with both feet and a step later our runner collided with him and they both fell to the ground. Seeing the ball go down the line into LF, there was no stopping him now. He got up and "raced" to home. The whiz in LF fired off another perfect throw to the catcher who tagged him out, game over. I protested to the PU that my runner was obstructed and should be awarded home, tie game. The PU said, "There was no "interference" Coach, it was incidental contact. I explained that the word was "obstruction" and that it occurs when a player not in possession of the ball and not in the act of making a play makes contact with the runner. I said he was no longer "making a play" after the ball went past him and that the PU should call obstruction. He said, "Nope, game over". Was that the correct ruling?