Arfield knocked the ball into the empty net after Rabbi Matondo collided with goalkeeper Craig Gordon in the penalty area, but referee Steven McLean blew his whistle for a free-kick to the home side.
The decision had little impact on the outcome with Rangers already 2-0 ahead at the time and playing against 10 men following the red card issued to Hearts’ midfielder Cammy Devlin for a poor challenge on Matondo.
Nonetheless, it appeared a harsh call with Gordon appearing to barge into the inrushing Matondo after palming the ball into the path of Arfield. However, speaking on BBC Sportscene, Stewart insisted the referee was right.
The former Hearts midfielder said: "It's a foul. It's a foul all day long.
"To be perfectly honest, it had no effect on the game.
"They thoroughly deserved their victory - but there's no doubt the referee got that one right."
Former Rangers striker Kenny Miller took a different viewpoint.
"I disagree (with the decision)," he said.
"It's Craig Gordon's momentum that's taken him into Matondo.
"It's not Matondo doing anything wrong there. He can't move, there's nothing there.
"It falls perfectly for Scotty. I didn't agree with the decision."