The PR agency writes what one of the world's most powerful CEOs tells them to write. They can strongly advise sounding sincere, but it's not their decision. I would venture that the reason so many corporate and celebrity apologies sound fake is simply because the client doesn't want to do a real one.

Sounding sincere doesn't mean they actually are, but it does mean they didn't let their ego get in the way of it, which is more than can be said about many who would be caught in a position like this, rich or not.