An elaboration of the above argument now appears on Shtetl Optimized, essentially as a meditation on the question: What strictly mathematical proposition would comprise rationally convincing evidence that the key linear-quantum postulates of "One Ghost in the Quantum Turing Machine* amount to “an unredeemed claim [that has] become a roadblock rather than an inspiration” (to borrow an apt phrase from Jaffe and Quinn's arXiv:math/9307227).

Readers of Not Even Wrong seeking further (strictly mathematical) mathematical illumination in regard to these issues may wish to consult Arnold Neumaier and Dennis Westra's textbook-in-progress Classical and Quantum Mechanics via Lie Algebras (arXiv:0810.1019, 2011), whose Introduction states:

"The book should serve as an appetizer, inviting the reader to go more deeply into these fascinating, interdisciplinary fields of science. ... [We] focus attention on the simplicity and beauty of theoretical physics, which is often hidden in a jungle of techniques for estimating or calculating quantities of interest."

That the Neumaier/Westra textbook is an unfinished work-in-progress constitutes proof prima facie that the final tractatus upon these much-discussed logico-physico-philosophicus issues has yet to be written! :)