I realized that I forgot to include the chopped scallions in the Black Bean Quinoa Salad recipe. So I updated the recipe to include that.
Also, I was recently reminded (by Cook's Illustrated) that most herbs are oil-soluble, meaning their full flavor isn't released until mixed in oil. So there might be reason after all to use a bit of oil in the salad. Next time, I'll try mixing the cilantro in a couple tablespoons of oil before mixing it into the salad. I'm curious to see if it makes a difference.