He tweeted "Her", which explicitly tells us it's a deliberate imitation of Scarlett's voice in that movie. And he tried to negotiate licencing her famous voice, which she rejected.
So it's more than just a coincidence, it's deliberate bad faith behaviour. Legally you can't misrepresent a product as being from a famous person when it wasn't, and he very much did that. I guess he was hoping she'd give in and accept the licensing agreement post-facto. But instead it looks he's in legal deep water now.