Each action says which visitors see it: everyone, or holders of a role tier in the page's space — admin, maintainer, member or observer, each including the tiers above it — or holders of one specific role. On a person's own page, the person counts as admin.

This decides only what is offered. Whether a published nanopublication takes effect is judged separately, by the roles its signer actually holds, so hiding a button is a convenience for visitors rather than a lock.