"or people with motor disabilities (e.g. those unable to use their hands)."

So... one of the WWDC design videos discusses this and several of the accessibility affordances that the headset supports. In short, if you "dwell" on a user interface element a small button will appear next to it. Dwelling on that selects the item.

They've actually put a lot of thought into accessibility, and I think this sort of technology could be life changing for some.