I think you guys know what to do.
Where do you see art theft? AFAIU, guy doesn’t claim it’s his art.
The guy already deleted all pics where they slapped the URL (literally, they took the art, claiming as their AND slapped their URL on it), but most of what’s left in the gallery is STILL not theirs (backwards google images search) and they do not source anything. And in some (now deleted) comments they claimed all of this as their own.