I had this same question. I use nutritional yeast all the time on my popcorn (and pasta), but I count it because it's so easy for me to overdo it. Here's the nutritional info for the Red Star brand, which is pretty standard -
Nutritional Information:
Serving size – 1 ½ tablespoons
Calories – 60
Total fat – 1g (0g saturated)
Sodium – 5mg
Total carbohydrate – 7g (4g dietary fiber)
Protein – 8g
It fits all the criteria for being Core, but since there's no consensus yet and I use more than one serving at a time I just count it. It's not too bad points-wise