That's probably because:
a) They already removed all of his stolen images
b) They found that most of the reports were false
c) The Help Desk is so clogged up (as it always is), they still have not gotten around to whatever reports have been filed on him. You try running a site with millions of people on it and have to go through thousands of support tickets every day, and half of them aren't even valid reports. 
And after going through his gallery, I'm guessing a) they already removed all of his stolen images. The admins don't always ban someone for art theft, unless they're a repeated offender. And nobody seems to be leaving complaints on his images or profile anymore, so...That's my best guess. 