I'll leave it up to the reader to dismiss any claims made in that post. But you must admit there's a big difference between "I volunteered at a prison, and this is what I personally saw happening often" and "I volunteered at a prison, and this is what the warden told me when I asked." The first one is at least direct evidence.

Having spent time in some of the nicest prisons in the world, I’d much rather sit down to have dinner with the violent criminals living in those institutions than the prison staff.

Even in Scandinavia, maybe 20% of the prison staff weren’t downright awful people. The rest? Bullying prisoners was their daily entertainment, nothing but cruelty.

>You have such a strong prior that prison administrators are arbitrarily cruel

Yes. Don't you?

Must be from one of those nicer places where that's not the case.