I'm not sure this logic applies to the OneWheel. They aren't self balancing like a SegWay where the average person can get on and be fine zooming around within a couple minutes. The OneWheel only does about half the balancing work, you have to do the rest, and learning to ride one can take days or longer. During that time you'll fall many, many times. It also doesn't take much to eat shit on it even as a skilled rider (1). You'd have to be a complete moron not to anticipate it throwing you at any moment.

Also the OneWheel, at least the Pint, can only go up to 15mph, and only on perfect conditions on the most aggressive settings.

(1) I had several weeks under my belt before my last incident and still ate asphalt because the cutout in the sidewalk I was going down as a little steeper than I had thought. The board was angled down just a smidge too far because of this, caught a lip where the asphalt met the sidewalk, and "physics took control".

EDIT: Addendum: That isn't to say parent comment is wrong about other boards/etc, or that the CPSC is wrong.