how do you know? The pistons still went up and down in their bores for 5000 miles....it could probably "idle" for the equivalent reveluntions and be broken in...no magic here.
It takes more than just the up/down motion to properly break in the rings. Otherwise all engines would be fully broken in at the factory by spinning them using electric motors.
The engine has to operate on its own power and under varying load conditions. Even the watered down owner's manuals state this. Where did you get your break in theory from?