If he can provide an email from the email linked to the account this can help, I believe the account is an official account and still at newbie stage so for they .ay have not used any address to be able to sign a message from such address.
But sure he have the email so other verification means may be applied to get him through, but people are advice to avoid using the security questions features.
It may seem like the user is a newbie, in fact he is, but given the date of registration I believe he isn't. The account was created in 2018. A lot could have happened in the last 7 years. And loosing access to a email address becoming a common thing now. So it would be hard to prove ownership if they haven't got the email anymore. Also there was another account with an identical name which got locked the same way (secret question) as OP did. Can't understand why would the OP consider opening multiple account for the same casino. Anyway, lets hope this issue gets sorted without any delay.