I am glad you got something back from Celebrity (RCI). I think it is just a shame that they deny boarding to people and do not compensate them on the spot. And it really makes you wonder who is making the decision as to whether you are communicable or not.
People can be communicable and have no symptoms. That is why the health form is really a joke, I am sorry to say. At least MSC has thermal sensors so they actually know who has a fever. But by the same token, you can have a fever and be past the communicable stage (however, I agree it makes a lot more sense to bar someone WITH a fever rather than without).
To not let you on with no fever or symptoms is really antithetical to everything they say about the form just being a formality and the final decison being made by a professional. I would like to know what that nurse was thinking when she denied your cruise.