Third Base Coach Interference?

 
With no outs and a runner on first base (R1), the batter singles to right center. R1 rounds second base and heads to third base. The centerfielder's throw to third base is wild. As the third baseman chases the throw into foul territory, he collides with the third base coach. The third base coach was in foul territory, attempting to avoid the ball and third baseman, but he was outside the third base coach's box. Because of the collision, the third baseman fell down and R1 was able to round third base and score.
 
The defensive coach insists that this is interference and R1 should be out (or at least returned to third base). What do the umpires do?
 
Call
On a thrown ball, if a coach intentionally interferes with a defensive player or the ball, or the contact is in fair territory, then there is an interference penalty. The rule is very different for a batted ball versus a thrown ball. In the situation below, the contact between the base coach and the third baseman was unintentional and in foul territory, so -- play on! The run counts.