You first said that Sky is "clearly an impersonation" of Johansson. Now you say that it's not a coincidence they chose Sky's voice actress. These are two different claims. It may not be a coincidence in the sense that they may have chosen Sky's actress because she sounds similar to Johansson. But that alone doesn't constitute an impersonation. Impersonation means deliberately assuming the identity of another person with the intent to deceive. So you'd have to demonstrate more than a degree of similarity to make that case.