It is common to use a brake on the Z axis. https://www.omc-stepperonline.com/stepper-motor-brake/ This will most likely require replacement of the motor because you will need a dual shaft motor. A pneumatic spring might be my first choice.
I found out the hard way that on the Thermwood it is important to stop the Z at the up limit else it will screw the nut right off of the screw and the bearings will fall out. Mine didn't fall because I had the older V ways on mine, and just snugged them up enough so the Z wouldn't fall.
You could just open the step signal to the Z drive on E stop or Z limit, but not disable the drive. Not the best solution but it would work.