If he put any appendage inside her, even with a condom, there would be DNA evidence. Just lightly scratching somebody's itch results in their DNA under your fingernails. DNA is very hard to completely erase from a crime scene, this isn't Sherlock Holmes times.
Also for the MaYbE BaRb WaNtEd iT crew, please interact with a human with dementia sometime. They don't recognize their own immediate family members, they don't know what their current situation is. Had a friend caring for an elder with dementia, the poor old woman shat herself and was talking about a baby because she thought she was giving birth. There is really no such thing as consent in that kind of scenario.
I can't see any outcome to this except for actual hard time for Chris. He doesn't meet the legal definition for an insanity plea because he shows awareness he knows what he is doing is wrong. In cases of rape/DV/abuse it's actually somewhat common to have the victim not want to pursue charges, but the state moves forwards anyways. If the victim saying "It's nbd I'm fine" was enough then almost no wife beaters would ever face justice because cycles of abuse are such that the abused often want to defend their abuser.
Also. The words "jail" and "prison" are not synonyms. Jail is where you go if (1) You've been charged with crimes, and either don't have bail or can't afford bail, and are awaiting sentencing / (2) You're serving a relatively short sentence of under a year or so and the jail has some room. Prison is where you go after you're sentenced and especially for any kind of felony.