They already issued a cash refund and miles. No airline issues cash refunds lightly. They already knew what he was asking and responded with an offer more generous then what they normally do. (Note I'm not saying that this was a correct amount, but it's much more then is to be expected)

Now they're likely to simply say, thanks, but we've already handled your complaint. We've issued a refund which we normally don't, and the matter is considered closed.

I hope he proves me wrong, but I'm not holding breath.