Maybe that's your take on it, but what they said in Marbury is simply that they must follow the Constitution. That's virtually a direct quote. The holding was phrased not in terms of what the courts had the power to do, but in terms of what they lacked the power to do - namely, enforce unconstitutional laws.
The didn't claim that the meaning of the Constitution is to be determined by their rulings. They said that they must determine their rulings by the meaning of the Constitution.
I thought, "So at what point are we justified in concluding that a court opinion is wrong?" was a rhetorical question so I didn't bother to answer it. I have no idea when we're justified. I know when I am.
Actually it wasn't a rhetorical question, but that was a rather rhetorical objection to the question. So substitute "you" for "we" in the question, while considering the points I raised at #564.
Now that I think of it, before you do that, perhaps you can answer if there's ever any justification at all for concluding that a SCOTUS opinion is incorrect, even if the legislatve and executive branches haven't objected to it.
Why do you ask?
I mean, millions of people think SCOTUS opinions are incorrect -- take abortion, for example. And they firmly believe they're justified in feeling that way. So?