"The sending off was a huge factor in the game as we were as good as Cardiff in the first 20 minutes," the Wolves boss said after the 4-0 defeat at Ninian Park.
"Whether our player caught Thompson or not I don't know, but it was never intentional. It was a terrible decision to send him off and that has cost us.
"For 20 minutes after being down to ten men, we were still as good as currently the best side in the division.
"At 1-0 we were still in with a shout as the Cardiff crowd weren't too happy and the second goal we conceded was just comical.
"Cardiff are a good side with two strong midfield players and a confident striker."