Interference with Catcher

[12UParent]

Situation: 12U game, R1 on 2nd, R2 on 1st, pitch into dirt, R1 and R2 both attempt to advance. Batter retreats out of box in direction of 3rd base dugout to get out of the way, ball rolls so that as catcher picks it up she has to throw over the batter for attempt at R1 going to 3rd.

PU Call: Ball on the batter, batter interference, R1 is out (removed from 3rd), R2 is on 2nd.

After the game, I think that the FU went to speak with the UIC who then explained it to the team this way. If the batter interferes with a catchers throw, that runner is out and the PU made the call correctly. Also it was said that the batter is obligated to get out of the box to avoid interfering.

Here is what I am thinking?????
1) batter erred in stepping out of the box and should not ever do this unless there is a play at the plate. The act of stepping out of the box puts her at risk for an interference call.
2) batter should have been called out, R1 back to 2nd, R2 back to 1st
3) play on

I appreciate hearing any of your thoughts...thanks
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Rule 8 Batting- Sec. 10. A batter shall not interfere with the catcher’s fielding or throwing by leaning over home plate. By stepping out of the batter’s box, by making any other movement which hinders action at home or the catcher’s attempt to play on a runner, or by failing to make a reasonable effort to vacate congested area when there is a throw to home and there is time for the batter to move away.
PENALTY: When there are two outs, the batter is out. When there are not two outs and a runner is advancing to home, the runner is out and the ball is dead unless the runner is tagged out, in which case the ball remains alive and interference is ignored. When an attempt to put out a runner at any other base is unsuccessful, the batter is out and all runners must return to the base occupied at time of pitch.