>Whilst it's funny these guys did this with AI I can't help but feel that they could have done this with someone who is halfway decent at accents and saved themselves a lot of effort.

On the contrary, it seems like they did save themselves a lot of effort by deploying the de-centralised 'deepfake' AI model. It would be significantly hard for the opportunistic scammers to go out talent-scouting locally, trying to match the exact vocal characteristics of a person. It would also create a vulnerability, notably the person hired to impersonate the CEO.