Neither you nor I have sight of the contract in question, but the primary reasons such contracts have language around refunds of card transactions needing to go back to the original card are to disincentivize card fraud by using a stolen card to purchase goods and then obtain a cash refund, to prevent "manufactured spend" by running money through a card to generate rewards or hit thresholds whilst then having it refunded in cash, and to avoid customers borrowing cash advances via a card without paying its penal cash advance rates.