If it takes less than a week for the maintenance, this makes perfect sense as to why the weeks before and after your cruise can make the stops. They apparently need to shut that engine down for a few days once the maintenance can be done (available mechanics, parts, etc).
You agreed to the terms when you signed the contract. You can't then come here and cry that you don't accept those terms. You may think that makes me an "RCL Tweaker," but I think it makes me an adult.