The trio each received the punishment after they failed to pull up during a voided three-mile novice handicap chase at the Scottish venue.
Johnny Go had fallen at the first fence and ran loose before coming down on the run-in. He was being treated while the race was being run and suffered a fatal injury.
'Stop-race' procedures were put into place by the racecourse executive while Johnny Go was being attended to behind screens near the finishing line, with the race subsequently declared void.
But Quinlan, rider of first-past-the-post Red Giant, Fox aboard Miss Joeking - the only other finisher - and Mulqueen, who was unseated from Here Comes Love after the final fence, appeared to ignore the 'stop-race' flag waved to raise attention to the stricken horse.
At a British Horseracing Authority disciplinary panel hearing in London, the jockeys were still found in breach but had their penalties reduced to the minimum of two days.
Paul Struthers, chief executive of the Professional Jockeys' Association, said: "I got the distinct impression we were not far away from being found not in breach or having just a one-day ban.
"On balance, two days seems a fair decision and is a victory for common sense.
"The way the 'stop-race' procedures were employed was almost entirely inefficient. Almost two minutes and 40 seconds elapsed after passing the screens when they might have been able to see a flag, but the only one they could see was between the final fence and the screens.
"The decision to void the race was taken as they went down the back straight, which means they jumped three or four fences for nothing, putting horses, jockeys and staff at risk.
"I don't doubt it was the correct decision to void, but I think this is the right time for every course to review their 'stop-race' procedures.
"Giving jockeys eight seconds to react is not appropriate, as we saw when Stephen's mount shied away from the screens and unshipped him.
"There's no point dwelling, it's a great result for the jockeys and they've been able to move their days to when there is no jump racing in the north so it should not prove too costly."