Barton was sent off after clashing with Tom Huddlestone midway through the first half, following a challenge by young QPR debutant Darnell Furlong on David Meyler.
The former Newcastle United man then appeared to punch Huddlestone in the groin, leaving referee Anthony Taylor with no choice but to show the red card.
And although admitting that he did not see the incident, Bruce was quick to condemn Barton's actions, while dismissing any suggestion that Furlong should have also seen red for the initial challenge.
Bruce said after the game: "I can honestly say that I didn't see the actual incident. I was applauding the initial tackle from both players.
"In my day both players would have picked each other up and said 'what a fantastic challenge that was'.
"I don't think it was a red card. If anything I think it was one of those fair challenges where both players were committed.
"So, I didn’t see the incident but everyone has told me what he [Barton] did and it's just ridiculous and one of those silly little moments."
A last-minute goal from Dame N'Doye ensured Hull capitalised on their numerical advantage, leaving Bruce delighted at the way his side persevered on what was threatening to be frustrating outing.
He added: "I think it's the first time we've put back-to-back wins together since last September [2013] and it's happened to us five or six times [conceding late in games] so it's about time it happened for us.
"There's nothing better when it happens. The relief more than anything, when Green makes the save 30 seconds before I'm thinking to myself 'Well it's one of them days'.
"Thankfully it was a wonderful cross from Robbie [Brady] and N'Doye was where every good centre-forward needs to be, six yards out, stuck it in the net for us."
