Treeby was guilty of being clumsy rather than malicious, but World Rugby has made it a prority to heavily discipline anyone who makes contact with the head in a tackle situation.
"From what's happened in previous games you probably could say that," said Umaga on whether he felt a card was deserved.
"We made the right call bringing him off because he definitely was concussed. We now need to make sure he follows the right protocols in trying to get back and play when he can.
"We've got to deal with the decisions that are made on the field. That's what we talked about as a group.
"We knew going into this game the South African referees had been giving away a lot of yellow cards, and cards in general, so we talked a lot about being disciplined and we would expect that consistency throughout the whole game."
When Umaga talks of consistency it is in reference to World Rugby's edict on appropriate punishments for high tackles and also a nod to his confusion that Blues wing Matt Duffie was red carded for one offside offence followed by a decision that he had dived on an opponent on the ground.
It would have to rank as the softest red card of the season and the inconsistency damages the credibility of rugby.
But some of that damage could be contained if Sanzaar simply front after the game has been reviewed. Referee Jaco van Heerden and TMO Shaun Veldsman got the decision on Treeby wrong. That's all anyone needs to say.
It was a mistake - a failure to follow the law. But it is hugely important that there is a public acknowledgement of that - not to humiliate the referee, but to give players the reassurance that their welfare is taken seriously.
If they hear about a serious commitment to protect heads and don't see it backed in action, then the whole business starts to ring hollow and rugby can't afford to appear to be insincere when it comes to concussion.
"I've got to go through the right channels in terms of reporting back - that's what we'll do to make sure we get some answers to some of the questions we have," said Umaga.
"There were some tough calls that we felt went against us but that's the way it goes. The Stormers brought a brutal intensity on defence and made it hard for us to build continuity in our game."