It is critical that one never leave a CNC machine unattended. This is considered a serious safety violation. Minimally, one should be in earshot of the machine - with practice one knows their machine and when the sound “goes off”. Ideally, one should be able to see the machine running.
In the best case, a crash simple breaks your tool and you loose your piece. A more serious crash can take out your spindle (probably not able to stop this but just maybe one can). In the worst case you start a fire.
I personally know two home CNCers who had a fire - one lost a detached garage, the other their house.
I’ve seen fires start in commercial settings, even though the machine was really never unwatched (a bit far away from it though). The fun one was the plenum of an expensive vacuum system. MDF top. Burned underneath the piece and the airflow stoked the burning. Serious smoke in seconds, even in the 15 seconds it took to the get to the machine and hit the E-stop. We had to yank the sheet off the top and do some serious fire extinguisher action until the fire department arrived (the alarms went off).
Obviously wood and plastic are the easiest material to have a fire with but it can happen with some metals as well. A spindle that crashes into stock and spins long enough can generate quite a bit of heat.
It doesn’t matter that the Nomad has a small spindle that may be easy to stop. Please don’t develop bad safety habits - stay near your machine. Something like a baby monitor will work… but not the best solution.