The LZW31-SN dimmer doesn't have the ability to disable the relay (not that jumps out at me anyway), but it does have the option to disable local control. However, "Off" always seems to be "Off" .. and that may just be the firmware design; so there is no "Off" sent, if the switch is already off.
That said, I considered writing something to accomplish this, and then I stumbled on one that seemed perfect and works exactly as I'm after (less the real-time dimming), but for some reason it is really hard to search out … so for anyone else that gets to the end of this thread, I've abandoned z-wave associations and my solution at this point is using the Switch bindings app by @jwetzel1492
