Do you think we should write "Stealing from this casino is forbidden in Our TnC?
No, you don't have to do that. There is already this in Paradice.in rules:
5.1. PERSONAL APPLICATION. The User is entitled to use the Service only for the private purposes. The User is allowed to use the web-site for his personal entertainment and does not have the right to create multiple accounts or use the web-site for conspiracies and/or misuse of the service.
Not sure if the bolded part existed prior to the incident or was added later, though.
However you can make it more explicit by stating that exploiting bugs or vulnerabilities is forbidden.