I had the same thought. My (white sharecropper fwiw) great grandfather went to Parchman (probably in the 30s or 40s) and supposedly came out broken and insane. I've always understood it to be a hell on earth on par with Alcatraz so it seems strange to see it framed as a place where people made some cool music :/
I did time in Parchman in the early 00s as I was transferred from prison to prison for RID (Regimented Inmate Discipline.) Intake was Rankin county, I started at Walnut Grove, then off to Parchman as I was too old for Walnut Grove (turned adult,) we buried people at Parchman. Then off to SMCI on the coast.
Contact the author and tell them the other sides. Every journalist I've met/worked with appreciates that kind of thing, another source/another side. They definitely will give you time.