I have not experienced the situation first hand but I have had the procedures explained to me by the Hotel Captain on the Statendam. They do take it very seriously. If you go to the infirmary complaining of an upset stomach and display signs of norovirus be prepared to be confined to your cabin and have all your dining room meals served to you there and all the unlimited room service you can eat. If you don't show signs of norovirus within 24 hours you are free to join the rest of the passengers. They aren't being cruel but a large outbreak is bad for everyone.
BTW: You get no compensation for being confined to your cabin.