Curious if you booked the Swolphin via Marriott or AA?
If directly via Marriott, I always charge onsite restaurants and resort purchases to my room because I have Gold Elite status from my Amex Plat(s) and Bonvoy Brilliant and that earns a 25% bonus points on the room rate and incidentals that are charged to the room, which means 12.5x points per dollar at most Marriotts. Then I’ll try to pay the hotel bill with a Bonvoy card for 6x points per dollar on Marriott purchases. If I paid the onsite restaurant, spa, gift shop, etc. directly with a Bonvoy card, I’d get the card’s 6x points whenever the POS is coded through Marriott but miss out on the 12.5x points that I could’ve earned if I had the charge added to my room.
If you booked through AA, then I’m not even sure if the Swolphin would recognize your Marriott Elite status and award you bonus points on your room charges. I agree with
@Alexle2007 that the terms of the Amex Offer require the charges be towards your room bill, or at least practically speaking settled at the front desk.
Just thinking aloud.