Would this also apply to real porn actresses who happen to look like Emma Watson?
"Under California law, intentional imitation of a celebrity’s distinctive and widely known voice for commercial purposes constitutes tortious misappropriation."
Intentional is the key word here. So I presume that if you look like Emma Watson and go with your real name, you're fine. If you pretend to be Emma Watson, then it becomes infringing.
But if the video says "this is a deepfake" and is not showing up in search results for her name, then it should be fine.
Its just that in the latter case, probably nobody is going to watch it, so the discussion is then moot anyway.