umpire/runner interence

Question
Batter hits ball to left/center field.  The batter rounds first and is heading to second but runs into the field umpire and falls down.  The batter gets up and returns to first base.  The ball gets thrown in to second.  The umpire stops play and awards the batter second base stating he would've made it if not for the collision.  Did the umpire make the right call?

Answer
Well this has proven to be quite a difficult question. Although I have not found a concrete answer, all of my research leads me to conclude that the umpire did not make the correct call. I have gone through the ASA rulebook multiple times, and it never alludes to this specific situation. That leads me to believe that the presiding rule is that the umpire is to be treated as part of the playing field, so that when the runner ran into him and fell it is the equivalent to the runner tripping over a stone on the field. Thus when the runner chose to go back to first, she should not have been given second.
  The rulebook gives very specific instances when the umpire is not to be part of the field (and thus can be a cause of obstruction). For example, lets say a runner is stealing 3rd and the plate umpire interferes with the catchers throw to third base. In this case, if the runner is not out, the umpire can call a dead ball and send the runner back to second. However, since there is no mention of a rule for when a runner collides with an umpire, I would assume that the ruling would fall back on the fact that generally speaking, umpires are considered part of the field of play. Moreover, in most cases (there are a few exceptions) when a batted ball hits the umpire, it is still ruled as a live ball and play continues. I was at an ASA game this year where a short stop was running for a pop up just into left field and she collided with a base umpire before she could catch the ball. Again, in this case it was ruled that the umpire is part of the playing field and the ball was live when it hit the ground.

I have also talked with some umpires from my league and they agree with my conclusion, but I will again say that no one I have talked to have found the specific ruling for this situation.