For context, I also hold the position that while being incarcerated obviously limits your physical liberty and maybe others, true liberty is a a state of mind; if you both take responsibility for acting on your authority and consider your incarceration unjust, your psychic liberty is intact and can't be mechanically confiscated from you. This might seem like a meaningless distinction, but the consciousness of one's fundamental freedom is what sustains many political prisoners, and conversely what authoritarians most fear and work to suppress.
I have to say I'm astonished by HN lately. I havae not seen so many badly rationalized apoloegtic arguments on slavery in my long life nor in 10 years at HN as these past three months.
In my mind, I'm making a distinction for a very real reason -- to say that, e.g., freedom of speech is a universal human right explicitly whitewashes over the fact that a tremendous number of people are deprived of that right.
What I want to make very explicit in the language I use is the idea that you have only the rights that you can reasonably pursue your daily life comfortably exercising. I find slavery abhorrent, as does pretty much everyone. Which is why I don't want to pretend like the problem just doesn't exist anymore, because after all, everyone unambiguously has the right to an existence free from slavery. They absolutely don't. There are plenty of people who can point to that idea as a travesty.
There's no specific number of people they need to convince otherwise to gain that right. They need to exist in a governmental, societal, political system that demands that that right be conferred on them. Until that happens, they don't have it and we shouldn't be saying otherwise.
Distinction you posit is in fact between a priviledge and a right. Priviledges are bestowed by a form of governance, rights exist regardless.
If we consider society in terms of game theory, law provides the rules, but the object of the game is to rewrite the rules through the exercise of power, for which you must employ strategy. The assertion of moral rights is a strategic objective.
On the other hand, if you steal from someone and they arrest you, then that person had the right to be free from your theft of their property.
You can assert whatever rights you want, but they aren't rights until other people agree that you have them and collectively decide that no attempt at punishment will follow you exercising them.