I believe that is incorrect no matter what Justices O'Connor and Thomas have decided.
The method prescribed for the people to elect the president and vice-president is indeed through electors, but that individual right is protected by the Fourteenth Amendment:
Section 2
Representatives shall be apportioned among the several States according to their respective numbers, counting the whole number of persons in each State, excluding Indians not taxed. But when the right to vote at any election for the choice of electors for President and Vice President of the United States, Representatives in Congress, the Executive and Judicial officers of a State, or the members of the Legislature thereof, is denied to any of the male inhabitants of such State, being twenty-one years of age,4 and citizens of the United States, or in any way abridged, except for participation in rebellion, or other crime, the basis of representation therein shall be reduced in the proportion which the number of such male citizens shall bear to the whole number of male citizens twenty-one years of age in such State.
Now if they had said that there is no provision in the Constitution for the direct election of the President and Vice-President they may have been correct. Maybe.
Because there are numerous federal and state laws that also secure the individual right to vote so that remarks about the lack of constitutional protection of that individual right are indeed specious and without merit.
The US Constitution is a bare framework of governance. The US Congress and the states fill in whatever is missing regarding, in this case, the people's right to individually participate in their self-governance.