The Belgian goalkeeper brought down Gylfi Sigurdsson in the area just before the hour-mark at the Liberty Stadium.
Sigurdsson picked himself up to fire beyond Courtois who most of the home crowd felt should have received a red card for his tackle.
But Sky Sports expert Quinn suggested that the changing of the red card rule saw referee Andre Marriner get the decision spot on correct.
"The keeper is in a good position, but he mis-reads the curve on the ball," Quinn said on Sky.
"It looks when he is running that he is going to get it, but it curves away from him and Courtois is in trouble as it bounces away from him. He is 18 inches away from making a good, clean tackle, but the red card rule has changed now.
"It was a genuine effort to play the ball, it wasn't just pulling down someone to stop a goal.
"As excited as everyone got in the stadium hoping to see a card, the referee got that one absolutely right."