I don't think they believe that. I think they just heard a chance to blame the President for something and took it.
Coincidentally, half of the population of New York City has an IQ below 100 :)
Most of them are not that smart. I think the majority truly believe this.
Looks like Zogby is trying out the weight ratio method of polling. Nothing to worry about, while Michael Moore may make up half the combined weight of New York residents, he doesn't speak for all of them.