[Adam]

Duketownie,
The point is that the distance is only for the purpose of the case play. 10 feet is just an arbitrary distance set by a writer, not by the rules committee.
Note the rule states that A1 is responsible for the contact in situation b because once A1 gets the ball, he is no longer entitled to the distance he would have been entitled to without the ball. Therefore, A1 is responsible for the contact if B1 is in position before A1 leaves the floor last prior to contact.
The rule is clear, time and distance are not relevant with a player control foul. Time and distance are relevant with regard to blind screens (B1 taking position against A1 without the ball).