I don't know how a casino's self exclusion feature works, so I will not be commenting on that. But I don't believe anyone would leave a significant balance on a casino and simply disappear or ask to have their account closed for good without withdrawing it. Even if they forget about their money, they should be reminded to withdraw it first. Having said that, this is still not a valid scam accusation because it lacks any proof. Just like in a court of law, you need proof for someone to be convicted of a crime.
Can you post everything you have that confirms your story and gives it some legitimacy? Also, have you tried to get in touch with @Stunna, their Bitcointalk casino representative? He is often active and posts on the forum.
This is him >
https://bitcointalk.org/index.php?action=profile;u=81292.