Slavery has to be one of the oldest and most widely accepted social and political institutions. The issue of self-ownership and its relation to the possibility of self-enslavement is a complex one. Historically, people have in fact sold themselves into slavery whether or not that was something that was either ethically desirable or even ethically possible.
I’ve read the Medaille’s passages but, frankly, I don’t understand just what point he is trying to make.
Could you perhaps frame your dilemma in your own words so that we can see as clearly as possibly just where your perplexity lies?