Regardless of how this particular argument has been made for this example, there is actually an under riding issue to this.
Authors sign contracts for the use of their works by a publisher. these contracts usually spell out exact restrictions for use of the content. The author's compensation for their work in creating the book is in various ways tied to the rights of use that they sign away with the contract. A publisher who takes a hit novel and wants to produce an audio book version of that book must have the rights to do so. If they do not, then they must strike a new contract with the author to attain these rights.
This is the basic foundation of how authors make money for their work.
The Kindle 2, by making text to speech a foundation part of how the book is sold, while perhaps an interesting idea for some users, may in fact be problematic from a contract standpoint.
While the Kindle 2 today may offer a monotone rendering only marginally better than watching Wargames, but that is a temporary condition. Technology advances and soon these readers might add more flavor to the reading. At what point does the Kindle interfere with the Books on Tape market? These issues must be resolved in order to proceed in an acceptable fashion.
The user of various readers for the visually impaired is an existing reality that has it's own arrangements in place with various publishers, distributors, etc.
To take a special needs argument and apply it as a defense of a device designed for the broad market, is a conceptual fallacy.
It's easy to point at the Author's Guild and make the leap to painting them with the same brush as the MPAA and RIAA but the publishing industry has some significant variations from those industries and to assume that the same motive drive them is foolish.
As an eaxmple. My wife is a new author. She went through nearly 4 months of contract discussions and negotiations during her initial sale of her first trilogy. The rights for the books are spelled out in explicit detail, using portions of the boilerplate contracts from both her agent and her publisher. One aspect of author's contracts is what published language(s) the contract covers and if it covers audiobooks. One cannot reasonably expect authors to give up their contract negotiations for their personal compensation for audio rights to their books simply because the Kindle 2 gives text to speech features, and what advanced form those audio features may have in the future.
So, while you read and debate this topic, avoid painting the topic as specific to one speaker and apply it as an argument on behalf of the authors who produce these works.