I believe their point was that it is still being abused by the prison systems.
Lots of questionable laws get passed. Lots of people get sent to prison for long sentences. When in prison they are being forced to work for virtually nothing. When they get paid at all it is usually 5% or less of minimum wage. If they don’t work they receive various punishments including solitary confinement. In short, slavery is still going strong, just with a legal justification.
I don’t think it is correct to say prison work is slavery. It’s certainly very similar, in the same way that sweatshop labor is like slavery, but it’s in its own distinct brand of fucked-up power dynamics.
But I’m also the kind of person who gets upset when you say a rabbit or ferret is a rodent, so I will concede that this is splitting hairs
I don’t think it is correct to say prison work is slavery.
I wouldn’t usually call it that either, but I don’t think it is that far of a stretch to understand those who do see it that way.
I’m not sure a sweatshop is a fair comparison since I have never heard that they imprison their “employees” between shifts, or throw them in small rooms if they aren’t will to work anymore.