Occam's Razor argues that Sam simply wanted ScarJo's voice, but couldn't get it, so they came up with a legally probably technically OK but ethically murky clone.
You want Brad Pitt for your movie. He says no. You hire Benicio Del Toro because of the physical resemblence. Big deal.
Having seen "Her" and many other Scarlet Johansson movies, I didn't think for a second that GPT-4o sounded like her. On the contrary, I wondered why they had chosen the voice of a middle aged woman, and whether that was about being woke. It wasn't until social media went hysterical, I realized that the voices were sort of similar.
Glover sued and won.