User blog comment:AYET/Talk about chapter 716 and episode 604/@comment-6920514-20130731215558/@comment-10543621-20130731234056

Agreed. It has also been mentioned that the only reason why Luffy's initial haoshoku simply knocked every weak willed people around indiscriminatingly was due to a lack of control. A person who has mastered control of his haoshoku are able to pick out individuals to impose the haki upon. Just like how Luffy previously knocked out all the fake strawhats without affecting the random passersby watching. In this case, both Chinjao and Luffy were obviously just slamming their haoshokus at each other.