He seems to enjoy fucking with the site, so far he hasn't done anything malicious. Of course, it's Friday, so the shithole was down for a good chunk of time. Like every fucking Friday.
So far it's just mental/spunk poking around, and TheVandalz chumping all the alts and multiple accounts. White-hat type shit. So long as you guys have basic site security and don't drump your fucking source code into posts due to errors (yes, that actually happened there), you should be "safe". Of course, any dedicated, true hacker could slice this place, or any place, to ribbons.