That is why they gave us a process to change things. They meant what they wrote. They understood the meaning of words. The only ambiguities in the document are the ones written into it by eyes that want to change the things in it without using the methods of redress directed within it.Which is less than helpful, because those things are in conflict, obviously. I've always thought they recognized that the country and the world would change, and the Constitution would have to be malleable to reflect that. The phrase "necessary and proper" is more than anything what the power of the government is based on, yet they don't include an explanation for what that means. The Constitution as a whole does not include notes on how it is to be interpreted.
The Constitution is not a "living" thing....it defines its terms clearly. They left it up to us to use its processes to change things as we deem fit in any day and age.
And I don't know why Roberts changed his mind.....but he was flat out wrong and so overreached in his reasoning that he should have been embarrassed.
Instead he took a tropical vacation. Winning!