[ManInBlue]

I think this is a ridiculous scenario. I agree with your point, first of all. Maybe not the entire thought process, but the point.

My point is simply that I'd like to see a pitcher make this move and maintain contact with the rubber. It's pretty close to impossible. And if he does, he probably didn't step toward first, so you have a balk anyway - FED ruling dead ball, the throw is irrelevent.

I don't think this scenario should have been mentioned in the case book, personally. If he steps toward 1B to make that throw, he HAS to disengage the rubber with his right (pivot) foot.

I don't think the feint to 3B in and of itself grants him to be off the rubber. But I do think he must disengage to properly throw to 1B.

editted to add - Your point is quite valid considering F1 can make this feint toward 3B and is not obligated to throw to first - the ONLY way this is legal (the feint to 1B) is if F1 has disengaged. Thus he MUST be an infielder at this point. Somewhere in the process F1 has to have disengaged the rubber.