That's pretty much what I do. Something like, "Dead ball! Stay right there!", or words to that effect, while pointing at the batter's box.
I don't think it matters how well you sell it. If the coach wants to argue, he's still going to argue. It should be a pretty brief argument (except maybe for you college guys that have to take a lot more grief from coaches).
"My batter should get first base"....Sorry, the ball wasn't completely inside the batter's box and in my judgment the batter intentionally stuck her arm into the pitch...end of story.
"That should be a strike"...No, the ball was not in the strike zone when it contacted the batter....'but, but, but"....Coach, are you arguing balls and strikes!
