I wondered when this would happen, so I looked at my "intermediary agreement" with David's from 2017. In that, there is a requirement that I book the room and provide the booking confirmation number, and not cancel the booking without David's contacting me. No where is there a requirement to issue a refund if the resort is unavailable. The agreement between David's and myself was "no refunds", just like the agreement between David's and the renter. Perhaps he has a better contract now, but the 2017 agreement leaves the owner losing the 30% check-in payment only.
What has occurred is what is considered a Force Majeure event, where the fault in fulfilling the contract is the result of a third party's action. Had I rented my points to someone, I'd offer to try to work with them on alternative dates (even though that is not permitted in the contract). If I couldn't work out a new date with the original renter, I'd go back to David's and tell them that they now have those points to use by the date that they expire. I would not consider refunding David's anything, since the agreement I have with David's is NO REFUNDS.