Scottish international Sullivan was given his marching orders by referee Graham Barber on the hour after rushing out of his goal to meet Brentford midfielder Paul Evans in the Worthington Cup second round, first leg encounter.
At the time contact looked minimal and having watched a video straight after the game, Graham was adamant that Sullivan had been harshly dealt with.
Graham said: "I've seen the incident on the video and there is no way it is a sending off. At the time I thought it was but now I've seen it again the goalkeeper hasn't touched him.
"Neil Sullivan has come out, the boy's got there first, jumped over him and then gone down. I couldn't have said that until I saw the video. Maybe that's why the referee thought it was a sending off."
Meanwhile, Graham insisted he wasn't overly impressed with the goalless draw despite having to deal with Sullivan's early bath and Sol Campbell dislocating his shoulder after 31 minutes.
Campbell was replaced by Ramon Vega while transfer-listed Ian Walker took over in goal.
Graham returned to a 4-4-2 system rather than playing all three strikers and handed Matthew Etherington and Stephen Clemence their first starts of the season. Chris Perry and Ben Thatcher were also recalled.
He added: "We had four chances on goal in the first half and another four in the second half. They had one in each half.
"I'm not too happy with the result. I like to win. We're creating chances but we've got to be more lethal in our finishing. Even when we went down to 10 men we could have scored.
"Fair credit to Brentford though. They plugged away and battled away. They must be delighted to be coming to White Hart Lane still with a chance next week."
George Graham was left in no doubts as to Neil Sullivan's innocence after the goalkeeper was sent off at Brentford on Tuesday night.