The torso has only its hands as a means of moving
No way he can run after Brook, yohohoho !!!
Edit: I just noticed something. Law apparently tells Luffy that they both have something they need to get back. http://www.mangareader.net/one-piece/663/8
And earlier Luffy asked him where Bepo was and Law did not looked pleased. If Ceasar is related to VP, and a crazy bounty hunter as smoker says, this guy could be holding Law's crew hostage. Hell, the 100 hearts thing could be his doing as well, Law's power is pretty useful from a weapon maker's point of view.
Also, read the scrip from MS, the translation is a lot better. No poof.