You can talk all you want about an international brotherhood, but these are people's livelihoods you're dismissing as unimportant.

And requiring American labor IS stipulating working conditions, because there is a very real difference between the working conditions of Americans and foreign sailors. This sounds like all you ever engage in is theory, while capital favors foreign workers because they don't have the same power (and expense) that American workers have.

Much of the American owned fishing fleet is entirely staffed by much cheaper foreign labor unable to leave their ships because their American company can get away with not applying for work visas. They didn't just happen to end up with foreign crews effectively held captive during port calls, they do it because they're cheaper and unable to easily challenge their bosses on conditions.

https://www.ap.org/explore/seafood-from-slaves/hawaiian-seafood-caught-foreign-crews-confined-boats.html

This isn't a case of an open labor market where everyone is on an equal footing and Americans simply choose not to do this work. Americans simply can't work for 70 cents an hour and bosses prize workers that don't have worker protections and can't demand more.

For many boat owners, the fishermen are a bargain: Bait and ice can cost more than crew salaries. Some of the foreign workers in Hawaii earn less than $5,000 for a full year. By contrast, the average pay for an American deckhand nationwide last year was $28,000, sometimes for jobs that last just a few months, according to government statistics. Experienced American crew members working in Alaska can make up to $80,000 a year.

An American crew has recourse and the force of law when an employer just refuses to pay their workers.

U.S. Customs and Border Protection and the Coast Guard routinely inspect the Hawaiian boats. At times, fishermen complain they’re not getting paid and officers say they tell owners to honor the contracts. But neither agency has any authority over actual wages.

When your labor solidarity philosophy leads you to support and defend the position of capital, a position known to depower workers and empower abuse, it feels like that's the point where you should be thinking about what the whole point is.