The concept is inherent within the Second Amendment.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
I think you are reading a bit much into the word ' security '
Not at all. And the concept is found in natural law.
Cruz is dead wrong if his comment is intended as an absolute.
And I think you're sticking your head in the sand. Opinions vary. Still forming one on this particular situation.
That said, even my laughable little bit of time reading Federalist Papers and quotes from our founders produced an understanding concerning the intent of the Second Amendment. Semantics be damned.