It doesn't really matter what Obama says about 9/11. He could declare it "kill a Muslim day" and they'd think it was insufficiently rage-filled. 9/11 has been the holiday for online conservatives. It was the day that gave them meaning. And they don't think it's theirs anymore, and they're mad.
The irony being, most of them hate New York City, and use the term "New York elites" with the utmost disdain. But they're more than happy to commandeer it to fit their own needs.