No actually he didn't stop. He was fucking up the hosting network K is now on. However they managed to stop it, and blocked all his incoming connections, as well as upped the security. It won't be near as easy to hit K now. They also have all his information so they might do something IRL about it as well. They are taking it very seriously.
No offense, but unless he admitted to hitting FK, a DDoS attack that used another mirrored network to amplify the attack is impossible to trace who did it, so i hope you have really good proof.