My sense is we have two people, and not necessarily the organizations. who are unaware of correct procedure and rules, and created statements that are inapplicable.
The first such person is the one employed by the rental organization who apparently has no idea how
DVC rentals actually work, because if he did he would know there is no verification procedure that the rental agency can possibly do with the the applicable
DVC resort. Moreover, he would also know that he cannot even communicate with DVC about the rental because DVC does not communicate with the rental agencies about a reservation made by a member. Unless the particular rental agency knows nothing about DVC, it would know that there would be no such suggested contact with the resort or DVC.
The second person is the DVC contact who sent the email asserting that using the internet to do a rental is a prohibited "commercial purpose." He, and possibly his immediate supervisor, may have just made stuff up because they had never before received a request to have the rental agency make personal contact about the reservation to verify its existence. Everyone uses the internet to do reservations and rentals, e.g., email is part of the internet, and no one else who has recently done a rental, and obviousy used the Internet, has been informed that DVC considers that illegal. DVC has taken no action to contest the existence and business of the online rental agencies.
The "commercial purpose" clause was created by the Disney lawyers who drafted the POS. Commercial purpose is a common term under a number of statutes and has the common legal meaning of being in the business of making a profit. The POS clause itself requires a "pattern" of rental activity before it can be thought of as a commercial purpose and simply using the internet to do a single rental is not a pattern of rental activity. DVC long ago created the presumption it would use to determine whether a member is violating the commercial purpose clause. The rule it created is that a violation of the clause will be presumed if a member does 20 or more reservations in any given 12-month period, and even that presumption can be defeated by the member showing he was not engaging in rentals for a commercial purpose (e.g., something the member could probably prove if most of the reservations were the member's and the member's purpose for the others, which were rentals, was simply to offset his payment of dues). DVC has done nothing to officially change that previously created presumption, and one employee staing a new rule, which that the employee provides to only one member, may not have had approval of upper management.