Why is it hard to believe that the SFWA's lawyer was given a list of authors and the scribd.com website address and told to sick'em. I could then see that list being pushed down the line towards the nearest para-legal or secretary to complete the gruntwork of piecing together the list of authors, titles and URLs. The list would have been inserted into a DMCA takedown notice, double-checked for simple mistakes and sent on its way via email.

While Mr. Pournell might have caught Cory Doctorow's writings, I'm almost certain any generic lawyer's secretary wouldn't and would have just seen that Mr. Doctorow was a SFWA member and continued on their merry way typing up the letter.

Also consider that most literary works aren't licensed in the same way that software is licensed, and finally like Cory Doctorow's books. It's likely it never occurred to secretary or lawyer, assuming that like most people are a bit further behind the curve of the publishing industry's trail-blazers than the science-fiction/computer geek community. An exception for a specific one of the SFWA's members wouldn't have entered their minds.

Finally, email is almost too easy to send and mistake emails happen all time, and only makes the mistake scenario even more plausible.