An interesting force out/obstruction

[Mountaincoach]

Hello. I'm new here and want to say hello from Kentucky. I coach a minor league (7-9 year olds) baseball team. I saw a play last night that was very interesting (at least to me after thinking about it). I think the umpire got it right, but I can see how it could be confusing. R1 and R2 on base. Batter hit a ground ball to shallow 3rd base area. F5 fields the ball and steps on 3rd for the force out, BUT at the very same moment, F6 ran into R2 and impeded her progress to third. She was probably about 6 feet from the bag, and it was obvious that the fielder was going to get the out (i.e. It wasn't going to be close). The umpire called the runner out and stated that the obstruction did not apply because she had no chance of beating the fielder to the base. Any thoughts or comments?