What is rule for dead ball with runner on 3rd?

[TravelCoach]

I could use some clarification for a U10 Cal Ripken League situation...

We play an aggressive team with a very aggressive player who, whenever on 3rd base, charges halfway down third base line after pitch is caught by catcher. He rarely "leaves early," so that really isn't a factor. What he'll try to do is time is charge to home with the catcher's throwback to the pitcher. We've had conflicting "solutions" to this, centered on "simply getting the pitcher back to the rubber." I've been told that if the pitcher is on the rubber and the catcher throws the ball back, making the ball dead, the runner (even if he is inches from reaching home) must return to 3rd. Yet, other umps have said that his reaching home would be allowed, as he executed a "delayed steal."

Can anyone shed light on this?