Apple blocking books that link to Amazon

Seth Godin reports that the Apple store is refusing to carry his new book:

I just found out that Apple (NSDQ: AAPL) is rejecting my new manifesto Stop Stealing Dreams and won't carry it in their store because inside the manifesto are links to buy the books I mention in the bibliography.

Quoting here from their note to me, rejecting the book: "Multiple links to Amazon (NSDQ: AMZN) store…

We're heading to a world where there are just a handful of influential bookstores (Amazon, Apple, Nook…) and one by one, the principles of open access are disappearing. Apple, apparently, won't carry an ebook that contains a link to buy a hardcover book from Amazon.

Seth is properly nervous about imposing demands on private companies about what they will or will not carry. But he finds what I think is the right argument in this case. first, the online marketplace for books simply as a matter of fact is dominated by three players: Apple, Amazon, and Barnes & Noble. This dominance imposes particular responsibilities for keeping such a crucial enabler of our culture open. Second, the vertical integration of this market — the dominate sellers of ebook hardware are also the dominant sellers of ebooks — imposes a similar cultural obligation.

Seth concludes:

I think that Amazon and Apple and B&N need to take a deep breath and make a decision on principle: what's inside the book shouldn't be of concern to a bookstore with a substantial choke on the marketplace. If it's legal, they ought to let people read it if they choose to.

(PS: It is genuinely irrelevant that the example of a book Seth was linking to is Too Big to Know. Although it pleases me to be linked to by Seth :)