But the Sky voice does not sound like it was trained off of ScarJo, or even off of someone who sounded a whole lot like her. There are some similarities, but, the voice sounds as close to, say, Rashida Jones as it does ScarJo. Yes, Altman posted a dumb tweet referencing Her which obviously looks to be in very poor taste, and yes they obviously wanted ScarJo herself, but does that mean they should not be allowed to have a voice that sounds even remotely similar to her?
It is standard and accepted practice for scriptwriters or directors to have a preferred casting in mind for a role, and when that person isn't able to be cast for whatever reason, for them to pick a person that fits similar criteria. What is different here?
The voices are different enough that I do not believe anyone as close to her as she claims would confuse the two. I pulled up a episode of Jimmy Fallon where she was on and compared the voice to one of the clearest audio videos of the Sky voice from the 4o demos, and they have different pitches, frequently different cadences to speech, etc. There are some similar mannerisms - there's a reason people see the resemblance - but if you isolate the audio of the two I don't think the majority of people would listen to them and go "Yep that's gotta be the same person," especially without all this context biasing their opinions.