hinos were beaten 13-12 after playing 58 minutes with only 12 men on the field after Moon was dismissed for a shoulder change on Saints centre Mark Percival.
Leeds, in their first game since last Saturday’s Tetley’s Challenge Cup final win over Castleford Tigers, led 12-2 as late as the 62nd minute, before league leaders Saints’ numerical advantage told.
Reflecting on the red card, McDermott said he had yet to study the incident, but he claimed: “It didn’t look like he made contact with the head. “If he hasn’t that’s a big call. It would be a wrong call in my opinion. I thought it was the difference between the two teams.”
McDermott congratulated Saints coach Nathan Brown for adjusting his side’s style of play during the interval to exploit their extra man.
“He did a cracking job at half-time,” McDermott said.
“It has to be said we made a couple of errors and we didn’t hold on to the ball, but how much can you ask of a group of 12 men in a game as intense as that?”
Two of Leeds’ substitutes, Robbie Ward and Brad Singleton, were not used.
McDermott said: “I just didn’t feel the need to put them on.”
Rhinos are now fifth in the table, with just two games away at Wigan Warriors and Hull – remaining.