I see one person talking trash, while the other person is feeding right into them.
So if I told you, you aren't half the man I am, that isn't talking trash? It takes two to banter.
If Jones didn't reply to Sonnen's remarks, no hype would ever be made and everybody would chastise Jones for not replying. He replies to comments made by Sonnen, and every chastises him for "feeding Sonnen."
Jones is trying to hype a potential fight, he could let Sonnen talk and talk, but he's choosing to go at it. He does this because it will make a potential fight between the two much more interesting and therefore, make him much more money.