Regenerative braking systems work by having a generator driven by the wheels that drives an electrical load - typically a battery charger. Charging the battery generates a current through the generator making it act like a motor but in the opposite direction to the way the wheels are making it spin.
Clearly storing charge in a battery is useless in a car whose only motive power is a rocket engine, so we can do away with that. We can just put a wire across the terminals of the generator. The generator itself can incorporate the axle as one of its parts, so it seems like it might work.
Of course, the wire will get very hot, so some form of cooling arrangement will be needed and since the wire is a continuous loop that goes through the generator, the cooling arrangement needs to keep the generator cool too.
Also, regenerative braking effect drops off at low speeds, so you'll need some ordinary disc brakes to bring the car to a complete halt.
This is all looking very complicated and heavy compared to the simple solution of metal discs and callipers.