For their internal politics, yes the PD applies. For general interaction, no, the PD no longer applies. You can also land on a pre-warp world if they're already buying Romulan Ale from the Ferengi. It's not like you can make it any worse once the cat's out of the bag. Consider that Kirk was sent to negotiate with the Organians back when they were thought to be a pre-industrial species; that was fine since they had already been contacted by some other people, including the Klingons.