A little more food for thought. We see complete combustion only under ideal conditions. Even with computerized micro-management, auto makers still find complete combustion elusive. I would think something would make it to your food, regardless.
However, I do not think enough would be left on the food to compete with the many other poisons we expose ourselves to, from sugar to soy to tobacco.
For health, I look more at your exposure to the stuff before it its burned. Lighter fluid alone supposedly pumps 15,000 tons of volatile organic compounds into the air annually before it its burned (depending on which group of wacko tree-huggers you listen to). Regardless, squeeze, squeeze, squirt, squirt, splash, splash, light, flame.... smell that? It is your brain cells dying. You just huffed chemicals, like the glue/paint junkie across town.
If your neighbor its an adult & wants to ingest dangerous chemicals, advise him of the dangers, then leave him alone.