Christopher Looby has published essays on Franklin in Eighteenth-Century Studies and American Quarterly. He is writing a book on the linguisticality of early American nationality, as well as essays on Richard Wright, nineteenth-century sensation fiction, and American masculinity.
1. Bernard Bailyn's biography, The Ordeal of Thomas Hutchinson, has a chapter on the scandal of the letters that is the best general treatment of the episode: entitled "The Scape-Goat," it foregrounds the metaphor that Franklin deploys to such effect. Instances of Franklin's use of the metaphor may be found in his Papers at 20: 381 and 21: 430, 431.
2. The work of Michel Serres, for instance The Parasite, provides an interesting conflation of the scapegoating device and the theory of communication disturbance via the figure of the parasite (parasite in French means "static"), who acts as a disruptive, noisy third party to an otherwise symmetrical exchange (economic or communicative). The exclusion of the interference, in the interest of restoring transparency, is analogous to the sacrifice of the scapegoat in the interest of restoring political/economic stasis. It isn't possible to explore this matter here, but the conflation of these two functions in the figure of the parasite is fairly prevalent in Franklin's writing.