Obstruction or Interference at Home?

 
With no runners on base, the right handed batter (B1) bunts. The ball settles in fair territory about 1-2 feet in front of home plate. As B1 leaves the batter's box to run to first base, B1 unintentionally contacts the catcher in front of home plate as the catcher was moving to field the bunt.
 
The coaches have very different opinions on this play:
 
- The defensive coach believes that his catcher has a right to field the fair batted ball without interference from the batter (as would be the case when the ball is hit to any other fielder). He would like B1 called out for interference.
- The offensive coach believes that his batter has the right to exit the batter's box and head to first base without obstruction from the catcher. He would like B1 awarded first base because of the catcher's obstruction.
 
Someone is going to be unhappy with the umpire's call! What is the call?
 
Call
As the play is described below, both the fielder and batter-runner were "doing what they were suppose to do" and "where they were suppose to be" . The catcher has a right to attempt to field the bunt and the batter-runner has a right to attempt to run toward first base from is original starting position in the right-handed batter's box. In the situation below, both coaches are going to be unhappy with a call of "play on". Check out Larry Barnett's "no-call, play on" in the 1975 World Series: