Criminals may well launder money through casinos. To do this, they need to negotiate with the management of the gambling platform. It is risky, but money laundering through online casinos is a common way for those who are engaged in illegal activities. The management of gambling platforms receives a good income from such shady activities.
They need to negotiate if that casino requires a KYC. It's indeed risky not only for the side of the launderer because what if the casino fake them and they will agree but the launderer didn't know that they will be reported to the authorities later on? It's also risky for the side of the casino because what if the launderer get busted out somewhere?
Authorities will let them confess if who is their partner and the launder will say that name of that casino. A gambling business is already profitable so if I were them I won't risk their reputation for some extra money. Helping a criminal is also bad but they must only help to prevent this kind of act.