I'll ask the devil's advocate / contrarian question: How big a slice of the human voice space does Scarlett lay a claim to?
The evidence would be in her favor in a civil court case. OTOH, a less famous woman's claim that any given synthesized voice sounds like hers would probably fail.
Contrast this with copyrighted fiction. That space is dimensionally much bigger. If you're not deliberately trying to copy some work, it's very unlikely that you'll get in trouble accidentally.
The closest comparison is the Marvin Gaye estate's case. Arguably, the estate laid claim to a large fraction of what is otherwise a dimensionally large space. https://en.wikipedia.org/wiki/Pharrell_Williams_v._Bridgepor...
We have 8 billion people, probability of unique voice and intonation is extremely unlikely. Imagine someone else owning your voice. Someone much richer and more powerful. No entertainment is worth putting fellow human beings through such discrimination and cruelty.