@Gordon0 You will not be overruled. If the guests cancel prior to the change, Airbnb will need permission.
@Natasha388 This is a difficult one, if it's only a one day stay, I'm more willing to provide a full refund because it's a bit away, BUT,
Airbnb will take it out of other payouts prior to their checkin. You will eventually get it back but not until that reservations checkin, which I find absurd. On those grounds I would decline, but that's up to you. Another option is to tell the guest you are declining because it is out of Airbnb's current policy and offer them a refund for the remaining amount(minus fees), if that night is booked again.