Whether or not the builde rof the town house development that you are writing about can legally make some of the units into rentals depends upon what the written covenants, conditions & restrictions state on the property assuming such documentation is recorded on the planned unit development. As such, I suggest that you carefully read any recorded covenants, conditions & restrictions with respect to your property. Most likely your answer will be in any recorded document. If no recorded document, then the developer can make the units into rentals.