Not to justify the actions of the shooter, but ringing the doorbell before breaking in is definitely a thing. It's a means of checking if the house is occupied - if you're just trying to steal things, an unoccupied house is ideal, and if someone answers when you ring, it's easy enough to make up an excuse and walk away.
A much better solution than a gun, though, is a security door (similar to a screen door, but more kick proof).
This kind of reminds me of Crispin Glover, from Back to the Future. He tried to negotiate a higher pay for the second movie, so the producers hired a different actor to play the role, but deliberately made the actor up to look like Glover. In response, Glover sued the producers and won. It set a critical precedent for Hollywood, about using someone's likeness without consent.
The article mentions they reached out to her two days before the launch - if she had said 'OK,' there's no way they could have even recorded what they needed from her, let alone trained the model in time for the presentation. So they must have had a Scarlett Johansson voice ready to go. Other than training the model on movies (really not ideal for a high quality voice model), how would they have gotten the recordings they needed?
If they hired a "random" voice actress, they might not run into issues. But if at any point they had a job listing, a discussion with a talent manager, or anything else where they mentioned wanting a "Scarlett Johansson sound-alike," they might have dug themselves a nice hole here.
Specifically regarding your question about hiring a voice actor that sounds like someone else - this is commonly done to replace people for cartoons. I don't think it's an issue if you are playing a character. But if you deliberately impersonate a person, there might be some trouble.