> We should be free to use celebrity voices for private purposes.
We are, in the US anyway. It's just when you distribute IP to others that things get dicey.
Why? Just because you would love to do something with it isn't a reason. What's a reason we should be able to do this?
"Because I'd love to" is a great reason to to do something. The negation usually comes from the other negative impacts what you want to do has, not because it's inherently an invalid piece of justification.
If there is zero difference to Johansson either way, and the use is purely private and never shared, then why is personal enjoyment insufficient justification?
Usually it is insufficient justification for those who want to profit off something people do freely for fun.