Earlier quoted context omitted.
Is it slave labour, I mean are they being forced to do it and not being paid for it, then sure boycott it. If NOT, and if it is an avenue for prisoners to earn money, benefits, then don't boycott it
Once you are already in prison it's hard to say whether you are forced to do it or not. It's not like you have a lot of employers and professions to choose from. And if the incentives include things like easier to get parole then refusing to participate would mean more time served. It'd be pretty hard to prove some labor is not "forced" in a prison setting.
So what? That's just serving the original sentence. That doesn't sound forced to me. Is it forced labor when someone chooses to take a community service option instead of being locked up?