While it doesn't quite go that far, it is pretty common for extradition from Europe to the US to be blocked for this reason.
Arguably, given how common solitary confinement is in the US, all extradition to the US should be abandoned.
> denying on something you are certain it is going to be reversed on appeal
Why would you think it would be reversed? It's fairly common to refuse extradition where the subject would be at significant risk of being abused/tortured/executed.