Redbird5,
I appreciate your words of experience. In this case, quietly approaching the parent would not have worked. I had used and have used this same approach many times. My instincts in this case were right on. Extreme conditions called for extreme measures. And this rule has always been looked upon as an extreme case, but that is because we expect our fans to treat the umpires and opposing teams with courtesy and respect. I make it my business to know all of our parents, and in this case I just knew (as did our other coaches) that something like this might happen. We also knew that if it did, bringing it to his attention, even in a public forum, would not have disuaded him. Pulling his son off the field, however, did keep him from continuing on the umpire towards a potentially disastrous confrontation. He knew it was because of his actions, the other parents knew, and the player knew it was no reflection on him. It was simply a rule, and that was the consequence if the rule was broken.
Our experiences, as a staff together for 15 years, have told us that parent/coach/player relationships can be quite emotional. I like to think I am objective, but I don't expect a parent to be objective about his own child. It is nice when they are, and it has been my experience that 90% are, but for the 10% who aren't, it can make for some awkward situations. I have found those 10% to be folks who behave one way to get their son on your team, and then change their behavior once the season starts. This encompasses fan behavior during games, discussions of playing time/roles, etc... Maybe we are approaching this wrong in addressing the sins of the 10%, but this is how we have decided to do things.
Best of luck to everyone!