The United man was dismissed on 74 minutes in the 0-0 draw that sent Hull City down to the Championship when he charged into a late challenge on McShane, racking his studs into his leg and catching the Hull man flush in the face with his knee.
McShane needed seven minutes of treatment following the nasty incident, which left him with blood pouring from his head.
“I could not see that from the bench, but I think it was a red card because the player needed seven minutes to stand up,” said Van Gaal.
“He continued after that, so it was not so bad as everybody thought, but it is very stupid for him [Fellaini].
“Next season he starts as a substitute [unavailable due to a three-match ban], because he has to sit in the stands suspended. That is very bad for a player and also bad for the manager and the team. It is worse for the individual player, because this season he also started in the stands.”
United were second best for the majority of the game as Steve Bruce’s men created plenty of openings during a nervy 90 minutes. They had two goals disallowed and found stand-in Manchester United goalkeeper Victor Valdes, who replaced the injured David de Gea, in fine form.
Van Gaal was full of praise for the opposition, who finished the season three points from safety after Newcastle beat West Ham 2-0 at St James’ Park.
“It was a special atmosphere – I have never seen fans of a team who are going to be relegated be so supportive until the end,” Van Gaal said.
“Their fans and the players were very positive, which made it difficult for us to equal their aggression and their motivation. They were fighting for a rescue, but we were fighting for a dream, to finish the season the proper way.
“That proved to be difficult, as you have seen. But still, we have earned a clean sheet, also with another goalkeeper. At the end, this game was not so important anymore because Newcastle won, which meant everyone had done their sporting duties.”