Perhaps we are reading the quote differently. In your hypothetical situation, "if the distances from the cable to the pivot and the brake pad to the pivot don't change, the geometry hasn't changed." This is exactly right. But as I read it, the quote envisioned the opposite hypothetical situation: If you put the brake pads as close as possible to the pivot, you have a strong brake. If you put them as far as possible from the pivot point on the same caliper, you have a weak brake. Even if the brake in question is a Campy NR. This explains why opinions about this brake vary so widely.