Grenham, I don't mean to beat a dead horse but I've never heard of an exception being made to their age requirement policy. I am in a unique situation where I deal with a very large number of bookings and communications with the cruiseline on a regular basis. With the explicit nature of their regulation on this and the reasons posted, one being "limitations of the shipboard medical facility, equipment and staff" as Dave pointed out, I'd be very uncomfortable even with a waiver in hand. I know the cruiselines make policy changes and can deviate from policy but that is not a low level decision that can be made by a booking agent. I have had forms that due to policy changes in the past have become invalid and will no longer be accepted. I would ask that, if the waiver you have in hand is valid, they remove the language from their site that prohibits such waivers. Contradictory language in writing is subject to the interpretation of the people enforcing the rules at the pier, not the person who booked the cruise or sent you a form. I've discovered in dealing with this industry, if there is a way something can go wrong it often does. The cruise will be at full penalty for cancellation at the time you arrive to board. If denied boarding, there is nothing available to you for compensation at that point, even insurance won't cover such a circumstance. Be very careful what information you're being provided and make double sure that there is no way you can be denied boarding BEFORE you arrive. If they will not remove the language from their policy on thier own site, I'd make other arrangements for care for the infant before the cruise. With limitations by the medical facility and staff, I'm not sure it's wise to sign such a disclaimer. What happens if your child does become ill during the cruise? Are you willing to take the chance that adequate care will not be available onboard? I would not travel by sea with a baby that age even with a form. Especially if it meant signing a form that acknowledged there is risk in doing so and you do so at your own risk. But that's not my decision to make.
Perhaps I'm paranoid, but I am cautious with very good reason based on past experience.