There was uproar about the video review during Fremantle's semi-final win over Geelong last weekend.
Dempsey appeared to kick a spectacular goal with a scissor kick, but the goal umpire signalled a behind because he thought the ball had come off the arm of Dockers defender Matthew Johnson.
The incident happened at a crucial stage of the game, which Fremantle won by 14 points. Geelong coach Chris Scott was adamant it should have been ruled a goal.
But the AFL Review Centre (ARC) ruled that the available video footage was inconclusive and so the goal umpire's call was not overruled.
"There are plenty of people ... who have said it's come off his arm (Johnson), versus his boot (Dempsey) ," Swann told AFL360 on Wednesday night.
"That's the debate. He's definitively called a point and the ARC ... aren't definitive that it's not come off the arm, versus the boot.
"So in that case, they defer it back.
"If he had called a goal, they would have left it go as well ... on the same basis."
It was put to Swann that the vast majority thought it was a goal.
"I'm not sure about that. There's enough doubt around that that they (ARC) didn't want to interfere," he said.
Also on Wednesday, Swann warned against the Western Bulldogs and Port Adelaide trying to manipulate the free agency system as they negotiate the Zak Butters trade.
There is speculation that Port's Todd Marshall might also go to the Bulldogs in return for high draft picks that would sweeten the deal for Butters, who is a restricted free agent.
"Let's just see what happens. There might be other things involved, there might be other picks and players involved," Swann said.
"We are speculating a little bit, but in the main it (the trade value) has got to be pretty close - or some semblance of close."
Swann also doubted that Scott Pendlebury's move to Gold Coast would affect the compensation that the Suns will receive for losing key forward Ben King as a restricted free agent.
King is keen to leave and expected to nominate Hawthorn.
"It would if he (Pendlebury) just came in as a free agent. Again, it's to do with the (compensation) bands," Swann said of the Collingwood great.
"But, having been through a few of these myself, Gold Coast will trade with Collingwood and give them a pick, and then that way their compensation isn't diluted."
