How is it ridiculous? The fact that purchasing a gun is the first step of shooting people is a good enough reason for most countries to ban the purchase of guns...
I don't think "because there's legitimate uses" is the differentiating factor, since that implies only kitchen knives have them. Self-defense is a legitimate use for owning a gun, for example.
There is no argument, why are people jumping to extrapolation? I'm pointing out that this DNN can be (and is being) used to identify people based on the ("any") detected faces. The possible usage is certainly related to the Parent comment issue.