He's discussing the nature of philosophy which is itself philosophical in nature; therefore, he's using philosophy to argue against the usefulness of philosophy.
This begs the question: Is he therefore advocating we shoot him? This would be one of the most clever ways to commit suicide. His gravestone would have to read "Trollololol".
On a more serious note (so you don't down vote me. Gosh.), it's already been said but philosophy's value lies in the framework for understanding Truth. With the exception of Absolutists and Subjectivists (and there aren't many that extreme) everyone is searching for something better and philosophy teaches people how to reason and what questions are relevant and will further the understanding of an issue of -everyone- involved in the argument. Socrates managed to get himself killed for asking questions which says something about their value.
Philosophy grants people the ability to understand, well, everything.