“steve2”: “It's worth noting too that the primary utility of a letter of disassociation is, not for the writer, but the local body of elders who will use it as evidence in support of the organization's shunning policies.”
Actually, that would depend on the particular writer, as everyone has their own unique situation – and their life history, personality, emotional dynamics, needs, and what really drives him/her are also unique and deeply personal. As such, therefore, whatever net advantage and emotional efficacy which would, or would not, be gained by submitting a disassociation letter could only be judged on an individual basis.
Surely for many, many folks, especially those having strong personal integrity, conviction, positive self-image, and maybe just a tiny amount of gumption and courage, the “primary utility” of a writing that letter would, indeed, be fulfilling the needs and interests of the writer! After all, it wouldn’t it be a most positive and deliberate step in a person’s recovery process?
If it were me in “Garrett”’s particular situation, I would write that letter in a heartbeat – and I wouldn’t care less if it was published in the Wall Street Journal.