Thank you all for your valuable input.

I know the miles are good/active because he's been very keen on preserving them through credit card activity. He used to travel a lot and may have saved them for a rainy day but now sees no value in it for himself.

Gift cards will earn him around 1 cent a mile and I don't view that as a great deal. But I'm sure there are people who value it a lot more than that and would pay him for it.