Why bring religion to gambling at first place ? Let's just see it as a person who is winning money from gambling.
Maybe because gambling is prohibited in their religion, place, or country, that is why. But even if not, it will still look inappropriate to see a religious leader do such an act as gambling, as we know that gambling is linked with many negative things.
I don't agree to ban the user directly from gambling but we can restrict a gambler who is always winning money.
After a certain win if the gambler keeps winning then casino owners can impose a restriction on him because that's how they can keep the business running.
In my opinion, it must be the opposite, like we can ban such individuals ( religious leaders ) and then allow a regular individual to win as much money as they can, as I see that this is also a problem in the gambling field (mainly in sports betting). If we lose a lot of times, they don't even complain, so they should try to be more fair sometimes because most of the times, they have a greater advantage than the players.