Such casses is like an auto banning mechanism, he may have committed a very strong offense and games providers have given report to other casino's and provider's to ban anytime he creates an account once detected he get banned.
Alot of such cases can not get revolved easily, since its already a concluded punishment granted after investigations, so it a bit hard for the account owner to rectify that issues at this point.
This must be a very serious offence, although I never knew they can report his account to other game providers to always restrict him when he tries to open new account with them. This is just the way you’ve said it, an auto ban mechanism and if they’ve come to a conclusion about it collectively, he may never recover the banned account and the rest may also be banned or the restriction worsening if he tries to do otherwise, violate other ToS which are not in conjunction or in compliance on the policy of the casino.