Here’s the post that I had seen.
Well, if it doesn’t cut power, it’s not really an E-stop. I can’t really think of a use for just cutting power to the steppers.
I’d remove the big button, check it’s specs, and repurpose as a true estop.
Many CNC controllers isolate the 5v line from USB from the MCU. I’m sure that’s what the SLB does, but I’m really surprised by the current estop function. You’d be better off wiring it in as a feedhold (that’s what I do on my Shapeoko).