It seems they don't play about this in some countries and I think that's how it should be. But if the gambling company is legit and doesn't scam people then there's absolutely nothing wrong with taking endorsement deals from gambling companies. In my country celebrities help to advertise scam casinos and this is actually the main problem and it's what must be corrected but no one cares to call them out
From what I understand, there was no scam accusation against the casinos but they are operating illegally in their country. By illegal it means they are operating without the necessary licenses and probably no documentation and no revenue to the government. The celebrities were arrested because their activities look like supporting that illegality, something the government see as unpatriotic and misleading to the general public. It's also important to note that as the casinos are operating illegally, it will be very difficult for the government to protect their citizens from losing money to them and in the case of the casino operators running away, there will be no way of getting them because they were not documented.
Operating illegally on its own is already a scam, no way that a casino that is operating without license can be trusted or be without any case of scam against them, we may have not hard anything related to that, but that doesn't mean there won't be cases like that, gambling operations is somewhat a sensitive thing and for sure countries generate revenue from their operations and for that any operation outside government approvals is already illegal and will definitely be treated as one of those that have scammed gambler in secrets.