Your original claim was that "slavery" means forced work without compensation, whereas "involuntary servitude" means forced work with or without compensation. Your citation doesn't justify this claim. It not just that there's a distinction, it's the nature of the distinction that I'm disputing.

> If I see forced unpaid laborers, I'm entirely comfortable deeming them slaves.

Yeah, you're comfortable with it because you've redefined "slavery" to mean whatever you want it to mean. But if you did a survey of native English speakers, and asked them if unpaid workers on a chain gang were slaves, how many do you think would say "yes", without qualification? I would be shocked if the answer were more than 20%.