As I mentioned before it may be that Jersey has people willing to pay £500 return for a Club Europe ticket or they are connecting to Business/First flights which more than cover costs but Y class might not have such high demand. There’s a lot more to it than fares on random dates. If BA were not making money on the route they wouldn’t stick around.
We’ve all been over this endless times. If there is business demand for such routes, carriers will add flights. They are not avoiding the IOM for some grudge.