Coaches interference?

[jonhillman]

I called obstruction on 3rd base coach on this play.
Please tell me if you would have done the same:

3rd base coach (8U Coach Pitch) is in the coaches box
and a runner is coming to 3rd after the ball is hit to
the outfield. 3rd baseban misses thrown
ball to him from the outfield (as the 3rd baseman stands
3 feet to the outside of the base); the coach stays put
with his hands on his knees allowing the ball to slow roll
between his legs while the 3rd baseman
has to stop his pursuit and move around the base coach,
obviously giving the base running time to continue toward
home to score.

After I made the call and gaveThe coach insisted that he had
the right to the box and did not have to move.