When problem show up some people immediately read the TOS which is bad action to do. They should read this while starting to register on their casino to avoid any issue and now this problem occur I think if I'm not wrong the accuser might be lose in this case since he violate the rules of the casino. But either way let see if there's settlement of the issue in good faith so that both parties can solve the issue and move on.
If you have signed up after agreeing to the all the terms mentioned there and raise concern afterwards how should they are responsible for it? They are not providing odds themselves and if they found it void they can cancel it but wait if they want to comment anything on the issue to provide better explanation.