Wing Afusipa Taumoepeau received a yellow card for a high tackle on Jamie Ritchie in Scotland’s 45-17 victory over Tonga in Nice on Sunday.
Taumoepeau was sin-binned and off-field officials carried out a bunker review, but the Perpignan flier was then allowed back into the fray. Scotland captain Ritchie failed a head-injury assessment and will now be stood down for 12 days.
The back-row forward will miss Scotland’s crucial match against Romania in Lille on Saturday, but will hope to return for the final Pool B battle with Ireland a week later.
Townsend was left frustrated by the decision not to award Taumoepeau a red card, and did not hold back in his own officiating review.
“I didn’t think we would get an explanation, but what they said when I heard the referee explaining it was mitigation in terms of height,” said Townsend.
“Jamie has failed his HIA and wasn’t able to return to the field, so it’s very disappointing that our captain, one of our key players, was hit in the head and had to be removed from the game.
“I think we’re trying to look at ways not to give a red card rather than what is an illegal tackle and should be a red card.”
Scotland shook off the blow of losing Ritchie to run seven tries past Tonga and keep their Pool B campaign alive.
After defeat by South Africa, Scotland must now beat both Romania and Ireland to stand a chance of quarter-final qualification.
Asked if Scotland would disagree that Ireland and South Africa are odds-on to reach the last eight, wing Kyle Steyn replied: “Damn right we’ll have something to say about that.
“Our focus will be Romania. We will have to get five points there, to make sure we then have a shootout when we get to Ireland in Paris.”