Way back in the Campagnolo headset installation instructions it is stated to complete the adjustment After the stem is installed.
We had a set of dropouts at the shop and clamped them in the hub/ skewer assembly to evaluate and perform the final adjustment with the skewer closed.
The reason to perform the final tightening of the Phil lock rings at the side that slightly spins was to reduce the false torque that the friction of the lock ring against the stationary bearing might transmit.