Yes, the cruise line company can make whatever rules they want. But I don't like to see them blaminging it on government regulations, which is just a lie!
Yes, a government can require that the build of the ship meet its safety regulations in order to allow the ship to dock at at its ports. But as to activities onboard after the ship has left that government's territorial waters, that government has NO authority.
I have no problem with any line which states "here is what we are going to do because we darn well want to!" Then, the free market will decide. What I do object to is a cruise line using non-existant government legislation/regulation as a false excuse -- because that is just a lie.