Not at all. He was honoring the intent of the Founders as to who were citizens. He added that it was not within his power to correct injustices and that any correction belonged to the political or lawmaking power.
"They operate within the framing of laws, and established custom in law, but within that framework they must decide upon the justice or injustice."
He was. Bear in mind that it took a constitutional amendment to end slavery, to make slaves citizens of the United States, and to give blacks (and women) the right to vote.
Nowadays, the courts wouldn't bother and would simply decree it. Which is how we end up with Kelo, Roe v Wade, the Kansas City school system, and all the other mistakes made by activist courts "correcting injustices" on their own.
He misstated the intent of the Founders, and their respect for the Natural Laws of Nature's Creator. As those Founders summarized those intents applicable in this case,
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable RightsIt was in his power to set Justice aright for Dred Scott and his family. Taney refused.
The lawmaking power does NOT include the power to take away "unalienable Rights". The government and the courts exist for what purpose? According to the Founders:
... to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governedBut what happens when the government makes laws or enforces the laws in ways that impair or remove the natural rights of men? The Founders spoke to dealing with that circumstance too:
-- whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish itThat is a court, judge or jury, acting in their role as agents of the people do have the right to alter severe injustice. That is especially so in the Supreme Court.
Remember that the courts, judge or jury, and officials whose role is to investigate and possibly bring charges against defendants, also have the role of interpose between sometimes harsh and unyielding interpretation of statute law.