Technically, he wasn't denied standing; the majority in Dred Scott said he wasn't a "citizen" and therefore couldn't sue under the provision of Article III governing suits between "citizens of different states." The majority's rationale was that, since the Founders permitted slavery, they must have intended that black people could never be citizens, because citizens have rights and slaves have no rights. The dissent, pointing to English and colonial cases which defined a citizen as anyone born in the country, said that blacks could indeed be citizens, at least in free states. The 14th Amendment overruled Dred Scott and codified the position of the dissenters in that case.
The 14th Amendment says that “persons born in the US (etc) are citizens of the US and of the States. It also says that no State may deprive any PERSON of due process and the equal protection of its laws.
The Roe court claimed that the word “person” in the 14th Amendment means persons who merit legal protection, not biological persons.
So the first part of the 14th Amendment, according to the Roe court’s definition, says, “All persons who merit legal protection born in the United States (etc) are citizens of the United States (etc)”
But the latest Supreme Court ruling had said that Blacks do not merit legal protection; they are property.
According to the Roe court’s definition of “person” as used in the 14th Amendment, the Dred Scott decision was that Blacks are NOT “persons” - not persons who merit legal protection. So even if they were born in the US they didn’t meet the 14th Amendment requirement that they be “persons who merit legal protection”, regardless of where they were born. If the 14th Amendment had said, “All rabbits born in the United States are citizens of the United States”, it wouldn’t apply to dogs born in the United States. Where the creature was born makes no difference if they don’t first fit the class of animal described, who would be citizens if born in the US.
The Roe court says that the animal that would be a citizen if born in the US is a “person who merits legal protection”. And according to the Dred Scott decision, that is NOT Black human beings.
It the 14th Amendment’s use of the word “person” meant “person who merits legal protection” as the Roe court claimed, then it never applied to Blacks - who at the time had just recently been ruled to NOT “merit legal protection” - and did NOT reverse Dred Scott, and did NOT give US citizenship to Blacks. And furthermore, it did not give them due process or equal protection either - no more due process and equal protection than fetuses, who are also deemed to be human beings who do not merit legal protection.
IOW, if the word “person” in the 14th Amendment means “person who merits legal protection”, then it never applied to Blacks and Blacks are in the same legal class as fetuses.