GBO have you ever "programmed" a diversion on an FMC? Unless you know what you are doing and are mentally coherent then there are so many errors that are going to be made it will make the whole effort pointless. You are also suggesting that if it was not a crew member then a FA or an engineer could do it from the back of the console leaning over the thrust levers. Sorry to all the flight simmers out there but programming an FMC on Flight Sim is not the same as a professional pilot setting up an FMC after having done the appropriate type rating then line flying.