My question now is are there any moral, ethical or legal obligation to bar a person from gambling after physically observing that he is mentally unstable?
I was surprised when I read the post title. There's nothing wrong if someone who is mentally unstable wants to gamble. Gambling is open to everyone, even those facing mental health challenges. As long as they can place bets and participate in the games, they should be able to enjoy gambling like anyone else. It would be unfair to deny them this right just because of their mental health. I appreciate that the attendant in your post was kind to all customers, regardless of their situation. Sadly, in my local area, I've witnessed people treating mentally unstable individuals poorly, refusing to sell to them even if they have money. They seem repulsed when these individuals come near them. I don't understand why mentally unstable people shouldn't be allowed to gamble.
Mentally unstable people can behave quite normally and place bets in gambling, but maybe this is the whole point - there are many more people who lose than those who win. Maybe the owners don’t want to offend these people in this way, because if they lose, it will be very sad. I’m sure it’s much harder to make money if you’re mentally unstable, and you can lose it very quickly. So the owners can see this as a reason for the risk in which, after another loss, such a person will come to them and declare that he did not control himself and provide some kind of certificate from a medical institution. I just suggested some options, but there may be more.
A valid point you made there, Sompitonov, but it's rare to find such things happening in gambling. However, the possibility is there, and casino need to stay aware about such dispute from happening. I've seen a man sue a casino for offering him more free drinks which made him lose out in the process. That he wasn't in his right self-control, the alcohol caused it. In a similar scenario for a mentally unstable player, the casino may not be held responsible for his mistake because the house is not meant to know whether he's mentally ill or not. As people perform differently, including mentally unstable gamblers. I don't think the casino would be penalized for allowing a mentally unstable person gamble, if he turns around to declare he wasn't in his right senses. The fault is on the player not the casino.