I do not think that the coin is lost, the casino have access to the coin because the address is there own, it was copied from the casino site. Even if I copied the right address but made a mistake and send the wrong coin and the transaction was confirmed. It has already gone to the casino account. I do not have the private keys to the address on the casino, the casino provides the address for me, so anytime I made deposit to the address they add it to my account. Casino normally makes rules because they know gamblers will always make a mistake as we are not perfect. Moreover,as the fault is from the sender the casino has the right to hold back his money or to return back his money because it is in there rules.
Since it is the same network, the money is in the custody of the casino. But the casino might claim that the wallet belongs to a third party, so they don't have access to it. But that's bullshit because they cant publish a wallet they don't have access to on their website. I think the casino should be lenient enough to credit the customer's account. However, the gambler should be blamed for this mistake because it is usually clearly written in most casinos terms of service.
Yes true, they might want to take the money the gambler transact but if they really say or mean that they do not have access of the coin the person sent and claimed the wallet belongs to a third party, then why do they fund the gambler account when he made the mistake the first time? If the person try to email the casino they will want about this they might want to deny the fact that they have access to it, but as you say that's bullshit,and it's true. The rules was there when the gambler made same mistake the first time and they refunded, now same mistake and no refund which means they want to take the money.