The "reckless modern" had "hurled" the name not at the sailors or the landsmen but at the songs themselves. "Them" must refer to "these last," which refers to the songs.

Grammatically, sure. But the question I am getting at is who was using the word 'chanty,' and what exactly is he alleging? Did the agent who introduced the word (i.e. in his imagination of it) come from among sailors or from among literateurs? Were sailors using a word that had become trendy among outsiders and then put into their vocabulary? Or does he believe sailors began using the word natively among themselves? If the latter, why so much disdain for the sailors' own language? What could he possibly think was their motivation to adopt the term or for someone among them to introduce it?

I am mainly using Russell as a foil here. His statements remind me of the yet unanswered issue of how/why/when the term 'chanty' came about -- the answer to which, of course, would help show from who/where they came.

The cotton-stowers and stevedores in many ports had the term "chantyman' or 'chanty" with them. There is a notable association with African-Americans, but it is not necessarilly the case that most were. Use of chanties (by whatever name) seems to have become common on ships (qualified by nationality, geography) by the Gold Rush. Assuming there is at least some significant relationship between the African-Americans' worksong practice and later shipboard practices...Did the term 'chanty' not come with the songs? Was it that the songs mostly came, and that only some 'deep' in-the-know would refer to them as 'chanty'? And if, for some time, the practice of these songs went on without most people calling them chanties, when/why did the term finally gain prominence? What would it come to prominence so long *after* the adoption of the practice?