I don't think he scammed. Stop spreading fud. He made a bet and didn't pay.
This has been debunked at least a dozen times already. When you promise to pay people if they do something, they do that something, and then you don't pay them, it's called a scam. There is no doubt in my mind that Matthew believed he had a chance of winning his bet and that if he had, he would have collected every Bitcoin he possibly could and gleefully pursued scammer tags for anyone who didn't pay up. "I was joking, I'm not paying" if you lose but "I'm serious, pay me" if I win is a *scam*, plain and simple.
Let's try a hypothetical. I say to you, "Let's flip a coin. Heads, I'll give you one Bitcoin. Tails you give me one Bitcoin". You agree. Assume the following:
1) Nothing I say suggests that I won't pay up if I lose.
2) You intend to pay me if you lose.
3) I intend to take your money if I win.
4) I intend to claim I was just joking if I lose.
Am I scamming you? Does it matter which way the coin flip lands?