The article states 'Aviation fuel' it does not mention 'jet' fuel for aviation turbine engines. Most commercial passenger aircraft have engines which run on Aviation Turbine Fuel often referred to as AVTUR the commercial grade being JET A1, Cooking oil can certainly be converted into a fuel for diesel engines. Many newer build light aircraft are fitted with diesel engines which run on JET A1 because it is cheaper than Aviation Gasoline 100 octate LL (Low Lead). I think that it is practicable to blend a percentage of 'cooking oil fuel' with AVTUR to make a safe acceptable mix for commercial use.