From that "other" thread:

Steve: Also of note is the reference to Americans (likely African Americans) using the songs to greater effect. A lot of Gibb's early references to the earlier songs are of African American rowers, in e.g., the Georgia Sea islands.

You've got Englishmen singing Canadian boat songs to South American Indians and Portuguese Jesuits translating Ch? Nôm to Latin and English, American and Italians trading songs on off the American west coast.
   
Why would African-Americans be likely, notable or... anyways different from the rest of humanity?