Saints boss Jim Mallinder agreed that Ryan Lamb deserved to be sin-binned at Welford Road on Saturday – but stopped short of criticising his player.
Lamb was given a yellow card in the 76th minute for blocking Leicester Tigers centre Anthony Allen off the ball.
Referee Greg Garner did not see the incident but referred it to the TMO, who felt the fly-half was at fault.
Lamb’s sin-binning cost Saints as they went down to 14 men for the final minutes of the game and fell to a 16-12 defeat.
But, though he had no complaints about the decision, director of rugby Mallinder was in no mood to blame Lamb, who had enjoyed a good game up to that point.
“I think that was quite a fair call,” he said. “I think somebody got that one right.
“What he did look to do was drop his shoulder a bit. If he’d have carried on on the same run he’d have got away with it.
“You can’t do that and that was the right decision.”
Despite Lamb’s moment of madness, Saints held out to claim the losing bonus point they deserved after a battling performance at Welford Road.
But with his side in contention for victory right up to the final whistle, Mallinder admitted thoughts of a win were on his mind.
“We definitely wanted more,” he said. “If you ever go with the mentality of just coming away with a losing bonus point, you’re going to struggle. But we’ll take the point.
“I guess if you look at the overall picture, George Ford could have kicked some more goals and they could have been further ahead but we thought we just didn’t get the bounce of the ball on a number of occasions and probably the call of the referee on a number of occasions.”