On & Off switching mechanism required

Hi guys.
I am using the following driver to control a BLDC motor.

I use 10k ohm variable resistor to control the speed of my motor and I should be able to hold the motor at a certain position with heavy loads. To do that, the manufacturer of the driver told me to connect pin 6(Motor Stop) to pin 8(GND) when the variable resistor is at its lowest(Motor stop and hold the loads) and disconnect pin 6(Motor Stop) from pin 8(GND) as soon as the variable resistor is rotated.
What is the best and simplest way to connect and disconnect pin 6 with pin 8 according to the variable resistor rotation?

Assuming no real current goes through this an Optocoupler or Reed relay could do the job.

You'd monitor the resistance of your variable resistor and drive the Optocoupler or Reed relay accordingly

an alternative approach could be to use a 10KΩ Digital Potentiometer

and have a user interface like a rotary encoder that would be used to drive the Digital Potentiometer and the Optocoupler or Reed relay through programming then you don't need to deal then with the analog signal

How to Build a Digital Potentiometer Circuit with a MCP4131

Thank you so much.
I can not use arduino for my application. I must use the driver with a variable resistor.
I am new with electronics so could you elaborate in more detail on how to hook up an optocoupler between the driver and the variable resistor?

Use a potentiometer with a "ON / OFF" switch at the CCW end.

Thank you.
I want to replace my variable resistor with this thumb throttle.

So basically, I want to make pin 6(Motor Stop) and pin 8(GND) to be connected when I let go of the thumb throttle and then I want pin 6 and pin 8 to be disconnected when I push the thumb throttle.
Could you tell me the most suitable way of creating this mechanism?

Do you have a schematic of the thumb throttle? Or interface specs?