I recommend that you read the reviews of the book on this site and others to get some context. Twiggef was writing a book for publication...I think a certain license may have been taken. The reviews will offer a bit of perspective from some of the people he castigates in his book.
For what its worth, I did enjoy reading the book, but have met / trained with many of those castigated, and they do not strike me at all as they seem to strike Twigger. They have quite a different take on some of the things he has to say, of course. I trust them.