Technically, you probably should not. I just finished a rental with him. I got the 30% day of check in and I assume renters went. It stayed as a reservation on my dashboard until the day after check out.
The problem with contacting them is that if you and the renter decide on something outside your contract, David’s would still need to approve, unless the resorts are closed, and then I think renter and owner may have upper hand.
IMO, if the reservations are at open resorts, I would not initiate any changes.