What's wrong with testing the waters? I wish all writers would do the same. Writing a book is a huge undertaking and any insights you could gain beforehand are welcome.
That would be such a tight schedule...surely they would have something in draft form at least. If this was someone's fulltime job, maybe I could see it, but really there's no reason for them to "test the waters". That was done with their blog, and also HN where you see the topic come up quite often with lots of discussion.
