Those are some huge claims the casino is making. Running a no KYC casino with good profits will be hard to sustain in a long term.
Besides that, its good that costa rica laws currently allows casinos to accept players form anywhere in the world but we never what might happen in the future.
If the jurisdiction changes and new laws restrict casinos to accept foreign players or wants them to have KYCs then the casinos claims will turn false.
I think the casino should have clause mentioned on their site that unless the laws changes they wont be demanding KYCs from users and will allow foreign players.
This way even if the laws change they won't get into major trouble.