Amazon didn’t extort anything from anyone. The choice for publishers was to sell their ebook versions at a reasonable price or not. Those who did not want to sell a virtual copy at a lower price would lose out, big time.
Apple and the publishers appear to be colluding to fix the price of the ebooks at a higher amount to rake in more money for a product that is inexpensive to produce.
The purpose for Amazon forcing publishers to charge $9.99 for e-books or sell none of their books on Amazon (e-book or hard copy) was to get Amazon a monopoly for the Kindle.