While the chance that I guessed the situation here wrongly is somewhat highly-probable, I dared myself to assume from the explanation given by their rep that the situation here is your account being flagged by their provider, so the one who actually investigating is the provider, not the casino. If I am correctly interpreting this, then the casino's hand are also tied. They're also waiting for verdict by the provider, just like you.
So, if I understand correctly the reason of the OP's account was disabled without allowing any withdrawals is because of his sports betting activities and possibly when involving arbitrage or fixed matches? So, could it also be that the OP has accounts with other casinos that uses the same betting provider?
If my assumptions are somewhat correct then the provider should clarify which specific rules the OP allegedly violated. More importantly I think they should explain why it's taking so long to respond and why they haven't followed through on their promise to address the case especially after two weeks of silence as the OP said in his previous post.
I believe this case is still unresolved and we can't guess any conclusions based on the limited information available for now. Hopefully, a representative from the casino will return and provide a detailed explanation of what actually happened, or if thir provider is the one behind all of this.
Not necessarily arbing or multi-acc, unless the provider specifically mentioned it to the casino. Like in casino-betting where a big win usually followed by an inquiry by the game provider to investigate the gaming activity to ensure there is no foul play, in sports-betting, sport-provider could also ask for investigation following significant winning.
Though, yes, there is a chance that the provider already told the casino the reason behind their request to hold the winning and to investigate.