And that it doesn't smashed into your face of you happen to faceplant. I'd be more worried about that.
Everyone says shit like this.
I have mine mounted to the CHIN BAR (which seems to gather a fair amount of attention and curiosity from other riders), and have had some good stacks... all that happened was the camera was knocked and pointed downwards.
Other crashes have just snapped the GoPro mounts long before anything else even looks like it's compromised.
Face facts, a camera anywhere on your body or helmet can cause damage.
It's just one of the many, many risks we take by riding bikes.
Having a camera mounted on the underside of the visor, in a bad crash that visor is more than likely just gonna snap off.