In fairness all holiday insurance policies clearly state that you need to pay an additional kings ransom to participate in 'winter type sports' & realistically most of us wouldn't give it too much thought in the spur of the moment as we donned our ice skates on a ship. It can't be a frequent occurrence, otherwise the litigious paranoid American companies like RCI would have signs & waiver forms plastered everywhere.
RCI does make you sign a waiver for the use of the ice rink, but really just take it easy or hold on to the side or just watch the professionals on the ice show instead. I let my kids use it and signed their waiver it really isn't a large or fast rink. What I can say being a seasoned RCI cruise passenger is they will look after you well if you do get hurt and will land a helicopter on the ship if needed. Make sure your insurance small print does aloow you to skate and if it's unclear get a written reply saying yes they do. Now the flow rider is the one to watch, my advice their is body board do not like me try stand up surfing and suffer whip lash when you fall (nothing the spa didn't relieve though).