I'm not very knowledgeable about this subject, but it seems to me that your points are refuted by the original article and the links you provide.

The BBC article you link to describes a single company in Spain that provides "ethical foie gras". It then goes on to quote critics who say "without the force feeding, it is not foie gras." It seems very unlikely that the restaurants being picketed are not using force-fed geese.

The original article talks about activists across the United States and Canada, not just NY state. Surely there are 1000 restaurants in the two countries that serve foie gras.

Finally, you third point doesn't seem likely at all. NYC recently banned trans fats. Are you claiming that restaurants are now going to use margarine that contains trans fats, but say they're "wans mats?" I highly doubt the city will buy that. Why would it be different for foie gras? For that matter, where does the original article discuss a goventment ban on foie gras at all?