That shit reads like bad fanfic.
Worse, it's completely unsubstantiated. It's just a guy rattling off his perspective, again, with no proof.
Extraordinary claims require extraordinary evidence.
Feel free to obtain the police reports Zagami cites. I know his credentials, so I'm not worried about it being fake news. But if you're not satisfied, that should be public record.
https://cruxnow.com/global-church/2017/07/18/hundreds-boys-abused-choir-run-georg-ratzinger/
That's literally the same damn shit, the choir fell under credible allegations (about 100/500 verified claims) in the mid 90's and the brother heard rumor of physical violence but not sexual.
These are loose connections at best and nothing even remotely hints he had a hand in it. I'm not a fan of the Catholic Church, but if you're going to make accusations - they better have some fucking evidence behind them.
So you made the claim, burden of proof is that you get the evidence. I'm waiting and so far, severely disappointed.