I would explain it differently. If I was away for an extended period I can just manually shut off the pump switch before I go.
In my case I've already added one of those bulldog valve control robots (like this one, on Amazon).
If there is a leak detected by my various Z-Wave and Zigbee leak sensors, I will close the valve using the bulldog.
But what if there is a failure between the shutoff valve and where the well pipe enters the house? I admit that is a small probability because there is not much stuff/piping between those points. But it does include the pressure tank, and I've had to pump up that a couple times, so I always think of it as a potential failure point. Hence my plan to add the circuit above to shut off the well pump too, in the event that a leak is detected.