Interference on dropped 3rd??

[DaveASA/FED]

Ok here it is was watching a 12U ASA game using the double first base) this weekend and saw this. Dropped 3rd strike and BR took off toward 1st she was about 3/4 down the line (well past the running lane) BR running in fair territory and F3 setup in fair territory catch throws over runner and it goes to right field, R1 scores from 3rd. Now the question is as I saw it I was debating interference on the BR, (BR out R1 back to 3rd) as she should have been in the running lane in foul territory. What do you all have? I know it's a HTBT but what are your feelings on this type of play?