If nobody said anything, would anyone know or care?

What if they just thought her voice set the mood. They couldn't get Johansson so they set out to find something similar and found it.

So what? They didn't say it was Johansson so no one could claim she endorsed it. How many times have you heard something on the radio/TV and thought it was some actor when it wasn't?

If she said nothing in public, nothing would have come of this. She could have writen them in private.

This is much ado about nothing and nothing happened.