Some currently-fashionable methods of literary analysis deliberately ignore author biography, but I don't think most people who favor those would claim there's never any reason for or value in examining the biographies of authors. I don't think they'd suggest people, say, entirely ignore the biography of an author forever and in all cases. Besides, it's common for one person to apply multiple approaches for a really deep analysis of a work, whether independently or together.

Plus, this is a review of a biography, so it's not the reviewer's fault the book is concerned with biography.