The annoying thing about this is the lack of evidence.
Do we really allow the government to ban anything it wants, even when there is no evidence it is harmful? Not an argument that it could be harmful, but actual evidence that it is? Just about anything can be argued to be harmful. If you want this precedent that things can just be banned with no evidence then you essentially accept the tenets of dictatorship. If they cited any kind of reasonable testing or evidence I would be fine with this, but they pretty much just say "Yeah, we suspect it might be harmful, so we banned it".
I strongly suspect Google Glass will be helpful to drivers and reduce accidents. It will probably cause a few accidents but on balance it will prevent more, because people will be getting directions without looking away from their windscreen as they now must do to look at a map or GPS. And never mind the hundreds of blinking neon signs crowding out our streets with the express intention of distracting us from the road to look at them - how about a ban on those?