It sucks and I understand the frustration completely as I have been there many times. I will never argue balls/strikes or out/safe (I might make a quick snide comment but never really argue) because they are strict judgment calls. But nothing is more frustrating than an ump getting the fundamental part of a rule wrong. If you are umping the game (even as a volunteer - especially in a large tournament like this) you should know the rule book to get these rules called properly.
I do agree that it seems like the wrong call as the ball was past the SS (especially since the ump specified the SS had a play on the ball) but it is still a judgment call. Not knowing where the OF was playing there may have been a chance for them to make a play on the ball as I know in some of these age groups the OF plays shallow (maybe even on the edge of the dirt) and it could have prevented that player from making a play (doesn't sound like it from your description). That is why it still has some judgment involved.
This past weekend I had a call where my runner was stealing from first and my batter foul tipped the ball and the catcher caught it. The ump tried to send my runner back to first because of a "foul ball". I calmly called time and clarified that a foul tip caught by the catcher is a live ball and the runner should be able to remain at 2nd base. We huddled with the base ump and homeplate ump and they discussed and the base ump overruled the home ump and the runner was able to stay. This was a situation that worked because the ump was open to discussion to get it right. This is a time that things worked. They usually don't work when Umps have too much ego and won't allow themselves to be "shown up". That is where most of the problems come in.
I do agree that it seems like the wrong call as the ball was past the SS (especially since the ump specified the SS had a play on the ball) but it is still a judgment call. Not knowing where the OF was playing there may have been a chance for them to make a play on the ball as I know in some of these age groups the OF plays shallow (maybe even on the edge of the dirt) and it could have prevented that player from making a play (doesn't sound like it from your description). That is why it still has some judgment involved.
This past weekend I had a call where my runner was stealing from first and my batter foul tipped the ball and the catcher caught it. The ump tried to send my runner back to first because of a "foul ball". I calmly called time and clarified that a foul tip caught by the catcher is a live ball and the runner should be able to remain at 2nd base. We huddled with the base ump and homeplate ump and they discussed and the base ump overruled the home ump and the runner was able to stay. This was a situation that worked because the ump was open to discussion to get it right. This is a time that things worked. They usually don't work when Umps have too much ego and won't allow themselves to be "shown up". That is where most of the problems come in.