It seems borderline, given that the person has a choice of when and where to perform it. But I don’t want to be near any borderlines here, so, yes. Morality aside, it seems very ineffective both in terms of punishment/rehabilitation and for getting value out of the person.

Well we're talking about morality, so is it morally wrong? I'm fairly sure you'd say conscription is morally wrong, but is jury duty morally wrong? I'm not sure a government can continue to exist without forcing people to work in one form or another.

As I said, it’s borderline.

Jury duty is an interesting question. I’m not a huge fan of the jury system, although it may be the best of bad alternatives. Maybe there’s no good way around this one.

I get that you’re trying to trip me up (and succeeding a bit), but penal labor isn’t difficult or borderline or anything like that. It’s a straightforward “we can make money by forcing that person to work, and it’s not illegal.” There’s no justification beyond, they’re a criminal so they deserve it. Obviously, criminal punishment has to involve violation of certain rights, but I don’t see any reason for it to involve violating this right besides liking money and wanting more of it.

Well I've already mentioned covering costs as a reason. Anything beyond that seems like a slippery slope.

You seem to think that forcing anyone to work is a slippery slope, and considering where we are now, there probably is some merit to that idea.

“Covering costs” is just a different way to say “we like money and we can get some by enslaving that person.” It’s not a moral justification for anything.