If the rider is actively balancing then it doesn’t need to immediately nosedive. In reality that’s the usual effect, but keeping a low center of gravity and trying to keep it balanced go a long way toward a smoother slide/roll instead of a faceplant.
The rider leans forward to accelerate the OneWheel, so they are not "actively balancing" - the OneWheel self-balances "against" their lean. Until the motor gives out, that is.
