He didn't say he ignored it. He said it was balanced out by something else. I mean, maybe. There's so much polling everywhere else that maybe one poll doesn't move the needle that much. I don't know how his model works, exactly. But I would think that this ought to move the average at least somewhat.
In fairness to Nate, it's really hard to calibrate a model when you only get data every 2 or 4 years, the data you do get is highly flawed (i.e. polls), and you can't really measure the accuracy of your model except from the national popular vote, which is meaningless.