An LED (or photodiode used as one) is a fairly simplistic device compared to an assembled receiver / transmitter. Just like you can burn gasoline in a car but you can’t push a car to turn the engine to make gasoline - it’s a complex system that really only works one way.
Not by “simply reversing the flow” it can’t. You’d need to remove and replace many components, just like the example of changing an Rx to Tx system