Your statement sounds like a contradiction.

If the development of batteries is so rapid, Rolls Royce not investing in electric engines and doubling down on fuel-burning engines instead could open them up for a book story worthy "disruption".

By the time batteries/electric plane engines suddenly become good enough, Rolls Royce might face themselves in a "why does nobody want our fuel-burning engines anymore" situation that will require multiple years to catch up to electric engine manufacturers. Multiple years of catching up that Rolls Royce might not have at the time they find themselves in the "nobody wants our engines anymore" situation.