I'd report it based on the fact that a guy like that hurts our feeding ground. Sure you have to be a total moron to believe what he's saying, but umm... has anyone noticed who we make our money from? uh yeah, morons!

I'd probably respond to him something like, "I'm 14 years old and my Dad lets me play on Pokerstars with his money. Does it make you mad that I'm taking all your chips? Is that why you keep telling lies about me?"