As long as there is no unauthorized accessing of the casino's server (hacking) going on there cannot and will not be any accusations of fraud.
As far as closing of one's account, that doesn't sound too likely. I think if anything, limiting the account is more likely but even that will take substantial and prolonged winning. In my mind, its the kind of bridge you want to cross when you get to it.
Finally, I suspect that you are talking about someone trying to sell you a system based on this supposed "flaw" in the RNG for only "certain casinos". I think it should be pointed out that this is simply a list of casinos that will pay for referrals and that claims of an RNG flaw are most likely bogus; i.e. the only accusations of fraud should probably be directed towards the person trying to sell you the system.