How can I answer an unanswerable question? The SCOTUS can no more declare a part of the Constitution to be unconstitutional than it can declare white to be black.
Yes, a person can be declared legally dead by a court, but that doesn't change their metabolic condition. If a dead person is found to be living by a court, they're still dead.
The supposed conflict here is that you're using the same word for two different terms. If a person is declared legally dead, then they are dead for the purposes of the law. In fact, the courts themselves recognize that legally dead does not necessarily equal metabolically dead, so there's no conflict.
The courts, up to and including the Supreme Court, have been known to hand down decisions that make about as much sense as declaring that white is black.
Why not? If we're going to draw this artificial distinction, why can't the court, say, declare snow to be "legally" black in color, while acknowledging that legally black is not necessarily the same as colorimetrically black?
In this age of emanations of penumbras I have no difficulty at all seeing an imaginary SCOTUS full of Gore nominees declare the 2nd Amendment to be unconstitutional due to being inconsistent with the 'domestic tranquility' and 'general welfare' elements of the Preamble, or some such nonsense. If they did so, would the 2nd Amendment no longer be "legally" constitutional?