"I don't know the rest of the song, but the verse given is clearly implying that the captains are snowflakes/libtards/leftists who are trying to destroy America by favouring the lesser races at the expense the poor oppressed Whites."

Yes, exactly, that was my point. The verse I quoted is the only reference to race/colour in the song and the song clearly doesn't regard "abolitionists" or "amalgamation" as good things.

The rest of the song is a grim and in many ways bleakly poetic vision of the hardships of life on Desolation Island. Were you to simply leave out that verse, you'd have quite a powerful good song, as it happens.

That's why it sprung to mind.