The individual term digital humanist may be problematic because it may seem both too general in not relating to a specific discipline or competence (thus deemphasizing the discipline-specific or professional) and too specific in emphasizing the “digital” part of the scholarly identity (if you are scholar) or giving too much prominence to the humanities part of your professional identity (if you are a digital humanities programmer or a system architect)
I agree with the authors critique of the term digital humanist, most specifically the point about the term being too specific in emphasizing the "digital" part, as I don't believe we exist in a digital vacuum where there could be something that is purely digital. I think that the world we exist in has a lot of digital technology at play, but it is almost redundant to emphasize something coming from a digital perspective.
I found an additional article (URL below) that also discusses this paradox in the term digital humanist. https://www.sciencedirect.com/science/article/pii/S2666659624000015?via%3Dihub