Argumentum ad ignorantiam: "Of course the Bible is true. Nobody can prove otherwise.", "pirate is not a ponzi because nobody can prove otherwise", "there is a giant teapot orbiting the sun, because nobody can prove otherwise". This also includes "shifting the burden of proof", btw.
No one is claiming he's not a Ponzi. All I see are a bunch of people claiming he is. Sounds like a logical fallacy on your part. "I believe in the Devil, and I'm going to make you prove to me that he doesn't exist or else I'm going to keep on believing and telling about he's the Devil because he's red and does parlor tricks".