The article mentioned that the judge threatened to stop Carnival from docking in US ports. That seems like it would have been pretty effective at getting companies to pay attention.

Shutting them out of the US wouldn't change much. It would stop their Alaska cruises, but everything else is mostly non-US countries. It is somewhat common to have fly to some non-US country to get on your cruise already. Those who drive to Texas or Florida to get one will be harmed, but for everyone else they are already flying so where they fly to is just a detail.

The real losses are to the US cities (in Florida, Texas, California, and Puerto Rico) that lose the tourism trade.

Now if other countries like Jamaica get on board things would change fast - but here is a case of each country acting alone loses, only by acting with others do they win. (and there is reward for cheating: if everyone else enforces this and you say you will but don't you get the tourism trade).

Of course if Carnival's customers start caring that will drive changes.

Carnival is a horrible unethical company. Our nation would be lucky to be rid of them.

There are plenty of other cruise lines. If one is thrown out, others can increase their business in the same area. There's no loss to any of those cities.

Not really, if you follow the ownership chain Carnival owns most of them somehow.