he can't prove that he didn't receive the funds back because he doesn't have either the private key of the note or the withdrawal LoG. All he has is a deposit LoG. But, given the current situation, even if he is lying, and actually has the private key of his note, he is no longer able to withdraw his funds.
Now, I'm not exactly sure who should make the call here, but I'd suggest giving the guy his money back, if anything's left in escrow, regardless of his mistakes. After all, his money ended up with whirlwind, and it's not like the casino situation where folks knowingly gamble away their money.
You may be on to something. One of the reasons he couldn't get a refund, was because if he's lying and still has the private key, he could claim it twice. Or someone else could show up with the private key.
Since the site is gone now, the only possibility would be if he withdrew already while complaining here. But if that would be the case, wouldn't WWM have noticed that and called him out on that?