Yeah, if the people on the cruise genuinely cared about the environment, they wouldn't be on a cruise, it's one of the most polluting ways to see the world, it not only directly hurts the ocean and everything in it, and everyone who depends on it (and not many people actually do any more, and like you say, most of those on board are probably eating animals), but the air too, and in a potential shift to battery powered ships, whatever damage making those causes, as well as other shit like by bringing covid to islands.

Blaming the destruction of the ocean on islanders sustaining themselves and not on the companies dumping garbage and pouring sewage and oil and god knows what else in to the sea, and the people who literally profit from dong that (like from them, on the cruise), is quite foul.