The midfielder was dismissed for a second bookable offence in the 86th minute of their 1-0 victory this lunchtime.
The manager told Sky Sports News: "The sending off was extremely harsh. He got booked for three or four fouls, the ref said, and rightly or wrongly he was on the yellow card. We told him he's got to stay on the park and stay on his feet, and I thought he did.
"The game was hard-fought but I don't think there was a bad tackle in the whole game. It's just because it's changing, the laws of the game are changing to the detriment of the game.
"We've got a player sent off today, in my opinion wrongly. I thought the ref handled the game very well but sadly I think he got that one decision wrong."
Rangers are 20 points clear at the top of the Scottish Third Division.