That's a bit scary that the government mandates that specific compound... I recently switched over to a Canadian brand of food-- hopefully there's not a similar law in Canada.
As far as thermal stability of ethoxyquin, I tried poking around a little and found an abstract of an article that claims that its effect as an antioxidant decreased by 60% at 150 degrees Celsius, but I couldn't find anything that suggested how much heat for how long would be needed to "burn off" ethoxyquin entirely. Any chemists in the crowd?