Just ignore him. I once posted a picture of my cat before she died (in the Cats stream) and I was harassed for it. The guy was going around saying that I raped her, and he kept using her image. He stopped for a while, then he started doing it again. I even brought it up to a site dev and he just deleted my comment.
He probably wouldn't have done all of it if I didn't tell him f**k himself. Or whatever I said to him, I don't remember.