Can the court compel you to provide a combination to a safe found in your home? There is some dicta that says that a court can compel you to provide a key to a lockbox and that is somehow different from compelling you to provide a combination. IOW, this conversation is not about what the law says but about what the law should be.
If there is a search warrant, I would say they can ask you to open the safe or take the safe until they can open it. I would be surprised to find that by putting something in a safe, you can prevent the police from carrying out a lawful court order.
-PJ