The «NAB Rewards» payment option is listed in the merchant interface on a pay page screen in the «Payment Methods» dropdown, but is absent from the payment options table in the documentation, and it is never mentioned by the documentation at all.
I have got a response from the AlphaCommerceHub support:
This allows a customer to pay with points if they are part of that scheme through the HPP, however is not in-scope for this implementation, you can ignore it.