Since the point of this is to dissect the play and make (or not) a call, I won't take the easy way and say HTBT to see the play.
As a general rule of thumb, I would want to see the catcher attempt to throw the ball before I will rule interference. Since F2 did not throw the ball, I don't see an interference call here. I'm not going to try to read her mind as to whether she intended to throw and pulled up or was just faking a throw.
As a second point, is the B/R really interferring? With ball four, her status has changed from a batter to a batter/runner, does this take away the "protection" of being in the BB? From the description, I don't envision the B/R doing anything she should not be doing. I would expect her to drop her bat and move toward first base. Would this play be similar to a bunt in front of the plate with F2 coming out to play the bunt and B/R running to first and they get tangled? I don't have access to the book here at work...I'm leaning toward a no call here.