It isn't about copyright, it's about passing-off, it's described elsewhere in detail in these threads what it means. It's about intention and what the customer believes. If customers might believe its SJ, due to samas tweets, general likeness in voice, and the context (voice assistant), the public info about them trying to get SJ to do this - that's passing-off, even if it wasn't training on her voice per se. There are numerous law cases about this.