My guess is either the OP is just throwing this out there for the fun of it and this never really happened.
However, if it did happen. I would say the OP threw a fit about the cabin steward stealing his credit card information. So Carnival asked the room steward not to service the room anymore so he would not be blamed for anything else. Since the OP believed the Cabin Steward opened the cabin safe and took things. Carnival farther protected themselves by not allowing any staff member into the OP's room. I don't blame them for this I would do that same thing. My hubby had credit card information stolen and it's impossible to say for certain who took it. We could blame the last place he used the card, but that is silly.