I've got Holden's book on the Witnesses; it's very good. He's a sociologist, and what he does is observe and describe the group dynamics and behavior, then use sociological theory to explain it. He's not making judgments; he's doing research. He followed a congregation in England for quite a while to do the book.
From the posted cv, his affiliation with North Carolina (a very prestigious institution), and the fact that he's ABD ("all but dissertation") in cultural anthropology, I'd say that Elliott is doing many of the same things--but he's still in his academic "apprenticeship." However, his background before UNC is mostly religious institutions (Baylor, Abilene Christian, Southern Christian) and he has a master of divinity degree. So he's a very well-educated Protestant--probably Baptist--and his interest in JWs is probably not entirely academic, but may also involve a desire to debunk their theology.
Of course, if it's really important to you to know, you could just ask him.