You want it to do this or it is just doing it and you want to control it?
In general the Unity 2018 and the latest Orion, etc. have improved handling a bit... if you are experiencing bugginess.
If you turn sensor tracking off, how can it track the hands - in order to know that the hands have exited?
LEAP MOTION hands are like a mouse cursor or tap by user, not an ordinary object in the scenario.
You could limit interactivity of the right hand under those circumstances within your scene, but stopping the sensor does not seem to make sense ...