Just a GA pilot here, but if the two yokes were going opposite ways, why does the captains yoke shear pin break and why not the shear pin on the first officer's yoke? Would it not make sense to assume that the captain is most likely more experienced and more apt to be making the proper (or desired) inputs over the first officer (except when training)?
Just as in this case, if the first officer makes an incorrect control movement that requires opposite correction by the captain, would it not make more sense for the system to lock out the first officer's yoke and leave control with the captain?