they should respect the rules or play no more.
We just have to accept their decision, it's their casino and they can do whatever they want with it and that should be the only important part of it. Without that, we are not going to end up with anything shocking like people pressuring a casino into removing KYC, that's not right and should not be happening at the moment.
If gamblers did actually take the time to read the TOS, and they found out they will face KYC policies on specific circumstances then they can take an informed decision about whether to play or not at that casino, and if a casino claimed they will not ask for KYC on their TOS and then they did so anyway then you can have a legitimate claim against that casino as they are promoting their services in a deceiving manner.