They got that decision right and should have gone further by sending Dixon to the bin for a professional foul. For a start, he had infringed around the side of a ruck and then compounded that by deliberately creating a shield and obstruction on Smith so his team could benefit.
In another match, Brumbies hooker Stephen Moore lashed out at a Reds rival who was obstructing him as he tried to guard his line. Claims for a subsequent Reds try were rubbed out, flanker Ed Quirk was penalised for holding and Moore was excused his reaction after officials looked at the big screen. Quirk should also have gone to the bin.
Crusaders' prop Owen Franks deserved that punishment, too, when he blatantly grabbed Stormers flanker Schalk Burger to stop him defending his line in front of his posts - a deliberate foul deserved a binning.
Sharks flanker Jean Deysel was banned for three weeks for stomping on Crusaders flanker Jordan Taufua who was holding his leg and impeding his ability to get to the next phase of play. Taufua needed stitches to close a mouth wound but escaped any censure for his part in provoking the incident. His deliberate obstruction should have earned him time on the sidelines.
This is where officials need to be more vigilant. If they bring these incidents to the referee's attention and players are punished then, rather than with a post-game yellow card, coaches will start reinforcing the message to their players.
Blatant and subtle acts of interference are meant to create an advantage or provoke a reaction. Late tackles, jersey-pulling, holding players back-they are all niggly tactics aimed at provocation.
Unless players are penalised or sent to the bin, they will continue to come up with ways of impeding opponents until officials take action.
There may be a few rounds when multiple players are in the dock but that refereeing interference will bring long-term benefits for spectators and the competition.