This would be a win for the millions of laborers that don't work in maritime shipping over the capital owners of the (~100 odd) jones act ships.

It would be a win for hundreds of millions of Americans who buy products that are shipped between ports. It would be a huge win for Americans in Hawaii, Puerto Rico, and other US islands.

It would be a loss for people employed building these vessels and it would be a loss for the companies that profit on building them. This is not a huge number of people.

As other people have mentioned, the issue is that the Jones Act has very clear advantages for the people who benefit from it, and it generally imposes very diffused costs on the people it hurts, even though the costs are very real. This is the issue with all tariffs.

Disagree. It would be a win for labor over capital.