To me the ability to change itinerary in the cruise contract is more about a good faith effort on Princess' part to deliver the cruise they sold you.
9/11, weather - none of that falls on Princess. Princess is more than privileged in that situation to claim force majeure.
Making the decision to cruise knowing you cannot deliver on the advertised cruise from the start is not good faith effort on Princess' part.
They are in the service industry, in a relatively high dollar vacation segment, and they are making the decision to lessen the customer experience on the Crown when other Princess ships, and other cruise lines are capable of delivering on theirs. Therefore this is not a circumstance out of their control. Its completely within their control to take ownership of this situation and make an honest attempt to satisfy their obligations.
Expecting customers to be "flexible and patient" in that circumstance may sound benevolent but it is grossly unfair, especially when I read the Sapphire and Diamond ships won't go into service until September. Someone can correct me on that if I am wrong but I've read two sources state that in discussion about the Crown.
A solution to this requires money, effort and time on the Princess Cruise's part, none of which they appear ready to expend