I've seen a table saw turn on without touching the switch, and have always unplugged ever since, even with the CNC.
However, once I added the Super PID, I no longer had the option of unplugging.
When I added the Super-PID, I left the stock on/off switch on my router, and I always turn it off when changing bits. This at least gives me a little extra safety, as both the PC would have to turn on the router when it's not supposed to, and the switch would have to fail for it to turn on when changing tools.
Be aware that if the router is controlled by the PC, that a PC crash can cause the router to turn on. Even if a momentary power loss causes the PC to reboot, the router can come on. I've seen it happen with mine.
You can always mount a plug near the router on your gantry or somewhere else so you can still unplug it.
On my next router, I plan on having a separate big red button just for tool changes, mounted near my tool change location.
Glasses and ear protection are for wimps, btw.