FWIW I put forth my theories on this is posts
10 and
16. They remain back there unmolested.
Let's be honest and boil this down to what it really is. For the Church of the NRA the issue here isn't gun control or the Second Amendment. Clearly it isn't, since neither Costas nor the source he quoted brought that up, and they know it.
The issue here is
blasphemy.
In proposing their analysis, the crime of Costas and Whitlock was that they dared to defy the prevailing dogma, suggesting that it might be possible that The Lord Our Gun might not be all He's cracked up to be,

that maybe He's even not deserving of the deification His followers require of not only themselves but the entire national discourse. And for that crime of heresy, they react exactly as, say, an Islamic fundamentalist would react to Salman Rushdie: the infidel must be silenced (or fired, or executed, depending which thread you read) in defense of the vicious attack on Our Load.
It's what religious fanatics do, and the prescribed resolution is always the same. And free speech is always the first casualty.
Ironically all this hair-on-fire foaming at the mouth about Second Amendment issues that were never brought up serves only to demonstrate the reverse of their supposed position, and validate everything that Whitlock and Costas said. The hair-trigger mentality: shoot first, ask questions later. Post first, read the commentary and the nuance later.
Except they stopped short by terming it "gun culture". They should have just come out and said "gun religion".