I personally feel this is RIDICULOUS. I have never heard of a hotel or cruise line banning someone for damage, especially this relatively small amount of damage.
If I had not caused the damage I would have never signed anything and they could have kept me onboard until I was arrested or they gave up.
I guess I'm banned from Princess for life. I fell in my cabin on the Island Princess and my stainless steel watch put a fairly good scratch (diagonally across the door) on the bathroom door.
I told our steward about it and he said not to worry. Within a couple of days the scratch was covered up. I don't know how they covered it up but you could still see where the scratch was if you looked at the right angle. They must have used a paint.
This banning for life for something like this is going to give the cruise line a VERY bad reputation and backfire on them.
I know there are three sides to the story but unless they totally destroyed the dressing table or there is "another" reason then Carnival is in the wrong.