I don’t think it’s sloppy at all. It’s by design.
David’s can provide whatever lip service they want, verbal or otherwise, that owners are “operating under the old agreement” but if the email clearly lays out that the new rental agreement with the renter, an email all owners will be copied on, that owners must make restitutions to the renter should things go south, David’s will have further evidence to provide the credit card company against any chargeback that they are off the hook.
Their piecemeal agreement situation with all these new rentals/rebookings sow enough doubt and confusion around liability that any owner should assume they are accepting far greater risks by rerenting.
As has been their practice in the past, David’s are continuing to bet that everything goes fine and none of this will matter, but this time they wised up and are no longer gambling with house money.