Most of the stadium felt Samuel's tackle had been a good one, however despite being perfectly positioned, referee Styles took the opposite view.
Ronaldo scored the penalty, paving the way for a 2-0 win and an unhappy Megson.
"It was a nonsense decision," argued Megson.
"When Rob Styles blew the whistle I thought he was going to book Ronaldo for diving. He did not seem to be sure what he was going to give.
"My thoughts on the tackle were the same as everyone else's in the stadium apart from one man. When the referee sees it again, he will have the same opinion too. It really sticks in the throat."
Megson added: "If TV replays take too long then we won't do them but from looking at other sports, TV can do these things.
"They talk about dropping the referee but what does that solve? It is just a symbolic gesture.
"Everybody knows what happened. Jlloyd Samuel won the ball. It is astonishing."