The chapter brings home why the White Clads wanted to get rid of Obi so bad. They knew what kind of person Obi is, that he's a the very definition of what a true leader should be, someone who can inspire others with his words and leadership.
And Joker also knew that well, which is why he needn't to tell Obi anything, because he already knew how Obi would deal with what is the most desperate of predicaments.