While an I.Q. of 120 is above-average, it is nowhere near the 99.9th percentile. It doesn’t even qualify for Mensa, which accepts people at and above the 98th percentile.
That being said, I agree that high-I.Q. kids think and act differently than the norm, and should receive the same amount of resources that kids on the other side of the “average” spectrum do. They are indeed “special education” students, even if they are gifted.