MK Dons boss Karl Robinson felt that it was a harsh decision to send off Swindon midfielder Nathan Byrne in the 1-1 draw.
Alex Pritchard's stunning first-half opener was cancelled out by Dons striker Patrick Bamford, after Byrne's 51st-minute dismissal for a late tackle on Shaun Wiliiams.
Robinson said: "I generally look at my players and there was no reaction from them to say it was a bad tackle.
"He has gone in to challenge for the ball, but it's a lazy challenge. You can get seriously hurt from it but, for me, I can't see that being a red card.
"I've had people sent off for an awful lot less, but if I was in Coops's shoes right now I think I'd be disappointed.
"Patrick had an easier chance in the first half to get us back on level terms, but he took his goal well.
"I was disappointed after that as I thought we came off it, I thought we were flat.
"We became sloppy and laboured in the way we moved the ball, which is why we made changes to galvanize them.
"But we should have had a winning goal, Dele Alli is not interfering with play because he's not challenged for the ball - George has kept himself onside so it should have counted."
Swindon carried the greater threat in the first half and Pritchard put them ahead after 17 minutes, curling a brilliant 25-yard free-kick into the top corner for his first league goal.
They were reduced to 10 men six minutes after the break when Byrne appeared to stamp on Williams' foot as the Dons defender cleared the ball.
Bamford equalised for the Dons just four minutes later, racing on to Darren Potter's defence-splitting pass to poke the ball past Wes Foderingham.
The Dons pressed for a winner in the closing stages but substitute George Baldock had an 89th-minute goal controversially ruled out for offside.