The right to the copy/text? The right to being allowed to reproduce? The copyright holder is the person who has the right to do so. Seems ok to me. In any case

The right to the copy/text? The right to being allowed to reproduce? The copyright holder is the person who has the right to do so. Seems ok to me. In any case, it’s a well established old term now while Unlicense was coined long after unlicensed was already an established word with a different (opposite!) meaning.