Al, it's a bit too complicated to explain here, but i'll try...
imagine a caliper bolted to a swingarm (standard single pivot), when the brake is applied, wheel rotation becomes swingarm rotation.
imagine a caliper bolted to the seatstay on something like an ellsworth dare, the seatstay doesn't rotate as is moves, it just moves up and down, this means that braking forces can't move the suspension.
back to the single-pivot, it doesn't matter where the caliper is mounted - on top of the swingarm, underneath the swingarm, wheel rotation becomes swingarm rotation.
In any event doesn't a brake just create a torque on the bike via the frame member it's attached to?
albeit the forces on by which it does so vary according to where it is attached
err... this one probably needs a diagram, but in the case of a single pivot it's mostly down to the height of the pivot above the ground.
anyway, if Cy ever makes a steel, 29er, 'Rocket', i'll have his babies.