Here's what I think:
Speaking USA rules - It doesn't matter whether it's been declared an IFF or not.
8.7.j.1: The runner is out when a runner interferes with a fielder attempting to field a batted fair ball or foul fly ball.
[1-3 Effect F] If the interference prevents the fielder from catching a routine fly ball (fair or foul) with ordinary effort, the batter is also out.
- The runner in OP made contact with a fielder trying to catch a batted ball.
- The ball in OP was fair when touched by the fielder.
- The fielder was unable to catch the ball with ordinary effort after being contacted, as evidenced by the drop.
- This contact impeded or hindered the fielder from executing a play, and is by definition interference (Rule 1).
- If judged routine fair ball by umpire, BR is out. (Which is also the IFF criteria)
My strict constructionist interpretation of the interference rule makes me think that it does not matter if the IFF has been
declared or not. There is no element of timing at play here. Of course, if declared, the batter is out no matter what. And before someone says it....YES...I know the ball is dead as soon as we call INT, so the drop might "never happen". We must still judge the batted ball itself as routine or non-routine.
Speaking Fed - I want to get two outs here, but I can't find rule support for calling the batter out unless the IFF has already been
declared (Rule 2-30). Case play 8.6.4.C covers this scenario. Again, reading the book closely, I don't think I can call the BR out unless IFF is judged (and in high school is can be "judged" all the way until the next pitch, 8-2-9 Note). Anyone with a rule cite or case play to say we always get the BR here no matter the timing of the Int call vs the IFF?
Speaking NCAA - The ball is dead at the moment of INT. The umpire judges the ball to be over fair or foul territory at that time. If fair, batter out. If foul, foul ball on batter. Yuck. At least we don't have to worry about the timing here.