sliding into home plate

Question
My son plays for our local Pee Wee team, and they play by baseball rules, with a few changes - one of them being "runners must slide on close plays at home plate - it's up to the umpire's discretion." Last night we had a game where it was our last at bat, we were down by one run (we were guests) with one out. Our batter hits a triple, and our next batter hits a ground ball to the short stop who throws it to first base. The coach sends our third base runner home as soon as he sees the SS start to throw the ball, our third base runner runs home but in the process barrels over the catcher who is standing on home plate. The ump calls him safe but the other coach starts yelling "He's out! He's out!" and the ump then rules him out saying he was supposed to slide into home. My question is if the first baseman made no attempt to throw the ball home is it considered to be a "close play"?

Answer
If there was no attempt at throwing the runner out then there was no play. However, the meaning for this rule is to avoid collision. My little league has the same rule. If it was decided that the runner intentionally ran over the catcher then he should be out and removed from the game.

My little league has it stated in the rules that any player who creates unnecessary and dangerous contact is out and removed from the game. If your league doesn't have a rule regarding this I suggest talking to a league official about it.