I personally don't see how money laundering can occur here (or at least on a massive scale). If he wanted to mix his coins he is much better off going to a coin mixer as opposed to a centralised casino.
$545 is definitely not a small amount in my opinion. Op could technically keep depositing that amount and withdrawing it again and again which is basically money laundering on a massive scale.
Besides, this is a very small amount, and it was clear that he wanted to bet on a single event (which has a lower limit than expected). Duelbits has the right to uphold their ToS, of course, but to me this is an honest mistake.
This isn't Duelbit's mistake at all since they were following their TOS properly. Fault lies on op who either didn't read the TOS and wagering tricks or engaged in money laundering.