Mr Clanky used to work for P&O / Princess Cruises and, as such, retains a deep seated hatred for the company.
As for the point about each ship being split into seperate companies, I'm not sure how Costa do it, but it is quite normal for each ship in a fleet to be owned by a separate holding company, this company can either be wholly or partly owned by the parent company who effectively charter and manage the ship or it can even be owned by an investment group.
In this way if the ship were to sink then mv Bathtub Ltd. would go bankrupt, whereas Dodgy Cruising Limited would simply continue to manage the other ships which they chartered from mv Rustbucket Ltd and mv Barely floating Ltd. and the only company liable for damages would be mv Bathtub limited and their insurers.
Dodgy Cruises limited would continue to trade, albeit with higher insurance premiums for all of their managed vessels and a slightly tarnished reputation, but without being exposed to any debts left behind by mv Bathtub Ltd.
Hope that clarifies it a bit.