Runner's Intereference/Obstruction

[wenriquez]

A Little help with this scenario that happened yesterday:

Man on 1st and 2nd, the 1Bman is playing in front of the bag with no outs.
The runner on 1B takes a lead as the pitch is being delivered, the batter hits a popup 5 to 10 feet behind 1B, near the foul line.

As the fielder (1B) turns to catch the popup, the runner runs into him and keeps him from getting to the ball. The 2Bman makes the catch while sliding, the runner on 2nd tags up and takes off for third uncontested.

I argue runner's interference. The first answer was he never took a lead. My response was if you miss the call I have no problem with that, however, I am looking right at it and the runner did prevent the 1Bman from getting to the ball.

The 2nd excuse came during a rain delay, and this one I wasn't 100% sure of but think it is wrong. Because it was a popup the runner is entitled to the bag and can run into the fielder.
What is the call in your opinion.