I'm glad you were able to get it taken care of.
I agree that the cruise lines should make people more aware that this type of documentation is necessary in some instances. Unfortunately they don't have to. Its ironic that they give you an idea of what to wear but skip over important issues like these assuming people will just know. Perhaps if more people make them aware that they would appreciate some guidance in this area they would provide recommendations in their FAQ's. However, I wouldn't expect any type of formal policy change coming in the near future. The cruise lines already have you release them from so many types of liability they certainly won't go creating policies that could open them up to any when they can easily just wash their hands of it.
Again, I hope you have a wonderful time on your cruise.