Then I don't think it really applies to this situation, since just as familial relations are superseding "business" relations in your example, certainly the prison relations change the nature of the business relations drastically.
But I think this is certainly labor, but the distinction between labor and chore is not so clear. I don't think it matters to the inmates, but I found it bizarre how confident HNers are that chores and labor are intrinsically different.
I think we started off on the wrong foot with the comparison. Even government recognizes some difference between chores and labor, as childhood labor is illegal but it's not illegal to have your kids mow the law (afaik).
Its really just an ever so tempting argument of semantics that is at this point distracting me from the real plight of prison laborers. But that's how the internet goes.
Both of them involve "work", but the objectives — the reasons the people doing the work are doing it — aren't the same.