I very much doubt it is as easy as it is made to look - few things on television are.
There is one thing to enjoying a cruise because you are free to go where and when you want, entirely another to have every single day scheduled from breakfast to bedtime with filming slots.
I am speaking on my first cruise in September, and I am not regarding that as a holiday in the slightest.
As well as presenting my talks, I will have to liaise with the Cruise Director and entertainment team to perform links and interviews for the on-board tv station, and when 'on view', I will be constantly representing the company and be on hand to chat with any and all passengers, answer questions, including over any meals, and generally be 'performing' for my entire time on board.
If I am doing that as a Guest Speaker, imagine what Ms McDonald will be doing in her time on board.
A cruise where I am just another passenger, that will be a holiday.