From what I read a list of all participants was not made public.

Having said that I find it extremely peculiar that this type of review/mediation/arbitration is even going on.

Does anybody know of anything like this ever happening before in the forum where a company worth multi-millions of USD$ engaged so deeply with some users to examine various bits of information (without giving away their trade security secrets) to show the alleged victim is actually in breach of their ToS?

It seems the OP (who is the alleged victim) is basically willing to share his KYC and various other information himself because if Sportsbet do it they are in breach of GDPR and various other data protection legislation and get sued. Part of the claim by Sportsbet is that the OP failed to pass KYC and part of the claim by Sportsbet is the OP had multiple accounts but on both counts they failed to disclose what the reasons were.

Regarding the multiple accounts, Sportsbet claim they applied more of a robust system than just to check the same IP address but for obvious reasons cannot disclose their techniques otherwise fraudsters and scammers will be lining up to sign up and take advantage.

Here are my reasons for not supporting any of the 3 flags against Sportsbet: https://bitcointalk.org/index.php?topic=5263445.msg54893685#msg54893685