I don't think panpsychism is common in dualism - the vast majority of dualists are not panpsychists. The argument of the paper is that "the United States is conscious" is a probable consequence of materialism. For your point to succeed, we'd need an argument that panpsychism is a probable consequence of dualism (or idealism, or so on), as opposed to merely a possibility compatible with it. Since materialists need to ground mental concepts in physical ones, they run the risk that their attempts to do so may have a broader scope than they intend (as this paper argues). Dualists don't need to ground the mental in the physical, so they don't run that risk.