You're confusing negotiating with throwing down the gauntlet. My take on this - and I could be wrong and don't necessarily agree with Carson - is that Carson is simply giving the Left an ultimatum. I think politically it's a good strategy and forces the low-information people to realize that the 2nd is not some right "given" to us by the gubmint.
Apparently, you misunderstand my view. Essentially, I agree with the author. BC proposes an intelligent discussion re our "need" for the 2d. That need is not negotiable and as a matter of fact, the need today is perhaps as great or greater than the need that existed when the 2d was ratified.
Now, if you contend BC is throwing down the gauntlet then I disagree. In any event how does one throw down a gauntlet and convince the ill-informed to change a position? {;^)