IRB Post 3- New York Times: Forbidden Planet "How I Killed Pluto"

http://www.nytimes.com/2011/01/02/books/review/Lord-t.html?_r=2&ref=bookreviews

Facts:
1)This article is a book review of "How I Killed Pluto" which was written by the man, Mike Brown, that was the person to have detected a potential 10th planet resulting in the banishment of Pluto in our solar system.
2)Apparently the book is not about the former ninth planet or even about astronomy, but rather about Brown's personal and family life.
3)The majority of the book is written in chronicle developments of Brown's life.

Questions:
1)I do not understand why when the potential 10th planet was found there was need to categorize/eliminate it all together. Astrology confuses me.