The USSC is not allowed to confer citizenship. Congress is given the power in Article I, Section 8, Clause 4, "To establish an uniform Rule of Naturalization ..."
And therein was the problem, and that's why the 14th amendment was necessary.
Once again you find a way to disallow freedom when there is a way to recognize freedom. As I pointed out before, Dred Scott lacked only the economic value of a slave to be a free man. Since he was born in the United States, he hardly needs naturalization, he only requires freedom from slavery.