I don't necessarily disagree with any of that, but we already have those issues while sentencing people to decades of anal rape. I'm not sure how much worse the death penalty is.
I'd be fine if we got rid of the death penalty in exchange for real deal life without parole. Put those people in a Parchman type set up and do whatever it takes to make it cheaper, and then use the money saved on prisoners in jail for non-violent offenses.
We demonstrably have worse issues in death penalty cases. Most heinous crimes lead to greatest pressure to conviction, which leads to errors, for just one path. Now maybe those issues/pressures would still be there absent the option for the death penalty (I think some would, some wouldnt), but at least the falsely convicted would still be around to possibly get freed.
And keep in mind we're not sentencing people like this to decades of anal rape. He'd be the raper, not the raped.