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.
That's the way it is now because of the 14th amendment!
Dred Scott was decided before the 14th amendment. Slaves could be citizens of the state in which they resided, but they could not be citizens of the United States without Naturalization.