The simple and correct answer is YES! A Realtor CAN show you both MLS listings AND homes listed by the developer. While The Villages developer would like Buyers to believe otherwise, the complete answer is this: The sales agents who work for The Villages sales department (read "developer") are allowed to sell both new lots and new homes in The Villages. They also can sell pre-owned homes that are listed by the developer. However, because they are not members of the National Association of Realtors nor members of a Multiple Listing Service they CAN NOT sell homes listed in The Villages by a Realtor.
On the other hand, Realtors ARE allowed to sell new or pre-owned homes in The Villages, even if the pre-owned homes are listed by the developer. But here's the catch - if a Realtor does sell a developer listed home, new or pre-owned, the developer will NOT compensate the Realtor - no commission split. This is the developer's way of trying to control Buyers, misleading the general public and discouraging Realtors from showing the developer's listings.
Many Buyers are turned off by this tactic, desire to work only with a Realtor, and it can be done.